Giordano Bruno: His Life and Thought
THE ITALIAN COSMOLOGICAL
HAVING taken a brief general view of Bruno's cosmology and philosophy, we turn to the six Italian works produced during his happy London sojourn. In them the main elements of his philosophy first found expression. The three Italian cosmological-philosophical volumes considered in the present chapter are perhaps the most important among all Bruno's writings. Each is dedicated to his beloved patron Mauvissière.
An Argument to each Dialogue of the work is incorporated in each of the three Dedicatory Epistles. These Arguments marshal the subject matter of each Dialogue under numbered headings which, however, are absent from the text of the Dialogues themselves.
a. The Ash Wednesday Supper (La Cena de le Ceneri)
We will pass quickly over the earliest of these volumes since we hope soon to have The Ash Wednesday Supper  in English translation from Miss Frances Yates. The work is in the form of a series of five Dialogues, or rather conversations, in which the lover of God, Theophilo,  represents the views of Bruno, "the Nolan" as he always calls himself, perhaps in order to avoid either the use or rejection of the monastic name. The Dialogues are in prose, interspersed with sonnets. There is much parade of learning and citation of ancient and modern authors. Certain of Bruno's London friends are introduced. Theophilo converses with Smith,  with Prudentio the Pedant and with a woman named Frulla.
He gives a satirical account of the persons who disputed with the Nolan in Oxford,  and passes to the Nolan's own views. After various digressions, compliments to England and reference to Bruno's Shadows of Ideas, Theophilo agrees to give an account of the colloquy of the Nolan with the doctors Torquato and Nundinio.  Then we hear of the invitation from Sir Fulke Greville to discourse on the Copernican theory; of the neglect of that nobleman to send word on the appointed day; of the belated arrival of the Nolan's friends Florio and Gwynne; of their hapless journey and the discourtesy of the London boatmen and loafers, almost matched by that of Greville's own lackeys and guests.
Before the Inquisitors at Venice Bruno stated that the Ash Wednesday Supper took place in the house of Mauvissière. It is therefore possible that his whole picture of the journey to Greville's house was introduced merely to express the Nolan's soreness at the unmannerly ways of the Elizabethan crowd. The discourtesy from which he suffered was common at the time. Mauvissière himself, most peaceable and gentle of men, had to remonstrate with the authorities against anti-alien manifestations, which went so far as to disturb the drainage system of the Embassy.
In the earlier part of The Ash Wednesday Supper, compliments to the Queen and to the English celebrities who had befriended Bruno alternate with complaints, amused, incredulous and often querulous, against English behaviour. Not until the third Dialogue do we pass to philosophy. Nundinio is cited as protagonist of the Nolan's opponents; Smith is very soon converted by Theophilo. The Dialogue opens with a glancing shot at those English gentlemen who know no language but their own, somewhat of a boomerang from one who in two years learnt no English, though incidentally we hear that Bruno had some command of French and Spanish besides Latin and Italian. Then we pass to an assurance that Copernicus not only meant what he said (in spite of the Preface inserted in his book by Osiander)  but that he was right in his views as to the motions of the earth. Moreover a whole string of names is cited of those who are said to have anticipated Copernican views, from "Nicetas the Syracusan Pythagorean" to Cusanus. Simple optical experiments demonstrate how easily we may be deceived by a wrong interpretation of our sense-perception, and this is applied to the apparent motionless central position of our earth.
From Copernicus the Dialogue passes to Cusanus and others who attained to that vision of cosmic infinity which was indeed an obsession or perhaps, we should say, a constant solace and inspiration to Bruno's thought. Theophilo then discourses on the plurality of worlds and speculates as to their inhabitants.
The fourth Dialogue disclaims any opposition to "true theology." Theophilo recounts the discourtesy of Torquato, "who can hardly exceed Nundinio so much in ignorance as in presumption, foolhardiness and impudence." Philotheo describes further arguments at the Supper, and narrates that the Nolan accused Torquato of misunderstanding Aristotle and then convicted him of misinterpreting Copernicus.
The last Dialogue, again citing the support of the early Greek writers, sets forth Bruno's own cosmological belief -- the infinite universe with its infinitely numerous worlds called by the ancients "ethera, that is runners, messengers, ambassadors who bring tidings of the magnificence of the single Highest." Their motion depends on the Necessity that is innate in them; their relative weight, lightness, motion upward or downward; cosmic metabolism which is propounded as the interpretation of the earth's local motion;  secular changes of the earth and considerations in relation to motions of the earth. Citing Aristotle as regards secular changes, Theophilo says:
Here he spoke as one who uttered prophecy or divination. Though he sometimes hardly understands himself, halting and mingling always somewhat of his own error with the divine frenzy, he yet speaketh for the most part and fundamentally what is true. 
Finally Prudentio is converted to the Nolan's views and opens a series of mighty adjurations by calling on the Nolan "by your faith in the highest and Infinite One" "to remain under the protection of the most illustrious and noble Mauvissière."
b. On Cause, Prime Origin and the One (De la Causa, Principio et Uno) 
The next work, again in Italian, was published in the same year and deals mainly with metaphysics. The Dialogues are represented as taking place in the house of Mauvissière. The Dedication to him, unlike the conventional adulation which we expect in writings of the period, expresses Bruno's transparently sincere affection and gratitude:
O illustrious and unique Knight, if I turn my gaze to behold the constancy of mind, the perseverance and the solicitude with which, adding service to service and benefit to benefit, you have conquered me, laid me under obligation, rendered me your prisoner: you who are wont to overcome every obstacle, to deliver from every danger, to bring to fruition all your honourable projects.
We may gain a further insight into Bruno's thought on Cause, Prime Origin and the One from the sonnets appended to the Dedication and Arguments. Three Latin sonnets, "To the Origins  of the Universe," "To my own Spirit," and "To Time" are followed by an Italian sonnet, "On Love" as the source of illumination, and a final magnificent apostrophe of "The Cause, Origin and Sempiternal One."
The work is concerned with problems of the Aristotelian philosophy but its conclusions are of course in opposition to Aristotle.
The views of the Nolan are again represented by Theophilo.  The other speakers are Heliotrope (i.e., Florio) and Hermes (Armesso) to whom are added in the last four Dialogues Dicson,  Gervasio and Polihimnio. As in the previous work, the reader must endure many diversions before reaching the real subject matter which concerns such themes as Form, Matter and Mind.
The first Dialogue discusses the speakers and refers with praise to the learning, eloquence and courtesy of Tobie Matthew and of Culpepper; and to Nizzoli, "un lexico, un cornucopia, un Nizzolio."  There are apologies -- not without cause -- for the strictures on England in The Ash Wednesday Supper. The second Dialogue proceeds to a consideration of what is meant by Origin and by Cause. Bruno conceived them as the internal and external factors respectively of the single, infinite universe, informed by the universal intellect. God the divine primal substance is unknowable, but may be apprehended through His works and especially by a study of the innumerable great celestial bodies. They are inhabited by living beings and are themselves endowed with life and pursue their courses through infinite space. Theophilo and his disciple Dicson emphasize that everything, however trivial, humble, minute has its part in the primal spiritual substance of the universe.
How far can we learn the nature of Cause and Origin by study of that which ensues from them? The relationship is considered of Efficient, Formal and Final Cause, and the Nolan's pantheism leads far from the usual Aristotelian interpretation of those terms. Primal origin is equated with matter, form with soul. Thus form is distinguished not by material nature, which is uniform, but by the acts and exercise of the faculties of those grades of being which it produces. Moreover, form and the soul are at once the whole and also every part of the whole.
The third Dialogue discusses "matter whose nature is conditioned by elemental origin rather than by cause or form." David of Dinant is cited that matter is excellent and divine.  The view is enunciated of the conservation of matter (a view elaborated in the Infinite Universe and Worlds as cosmic metabolism). No substantial form loses being, says the Nolan. One constant formal principle, even as one constant material principle, seeks expression through diverse, ever-changing manifestations.
Matter can be considered as Potentiality or as Subject, but the Supreme and Divine, comprehending the whole universe, is the total potentiality as well as the whole of Being. Parts do not fulfil their whole potentiality; hence death, corruption and vice. Intellect cannot comprehend this absolute act which is one with absolute potentiality of the universe. No eye can reach this most exalted light and this deepest abyss. But it is expressed in Holy Writ of the Divine Spirit. "The darkness hideth not from thee; but the night shineth as the day; the darkness and the light are both alike to thee." 
The fourth Dialogue then continues the discussion of matter. The thesis of Plotinus is cited that if in the intelligible world there is a multitude of different species there must be something in common behind the peculiarity and distinction of each. That which is in common is matter; that which is peculiar and distinct is form. Ultimately, matter is one with Act, and in incorporeal things, matter comes to coincide with Act as potential Being coincides with Being. Moreover, in absolute potentiality and absolute act there is no distinction between matter and form. For this (which is both matter and form) is the ultimate purity, simplicity, indivisibility and unity, and the whole; though if it have certain dimensions, figures and distinction, quality, it is not absolute or the whole. For the form which comprehends all quality is no single one. Thus Averroes understood the matter, and though he knew no Greek, he comprehended the peripatetic teaching better than many who read Greek. Being perceptible and explicit is not a primal quality of actuality but is an effect thereof. When, following Aristotle, we seek the perpetuity of form in Nature, we find it, not in the fixed stars nor in ideas but in the bosom of matter, for matter is the fount of actuality. Matter is ever the same, immutable, though around and within it is change. The compound is altered, augmented, diminished, changes position, suffers corruption but never does this happen to basic matter. Matter receives nothing from form. What can the corruptible give to the eternal -- what can one imperfect being, as is the form of sensible objects, always in motion, give to a thing so perfect that if rightly regarded it will be recognized as divine? Perhaps this was the meaning of David of Dinant, not understood by those who reported his views,  It is matter which conserves form; therefore it is form which desires matter for its conservation since, separated from matter, form loses its being. 
The fifth Dialogue concerns the One, completing the foundation of the edifice concerning natural and divine knowledge. Once more we learn that the universe is One, infinite and immobile. Matter and form, potentiality and action, though logically distinct, are physically one and infinite, immobile, indivisible, without distinction between whole and part, between origin and result (principio et principiato).
Again and again, the Nolan attempts to give expression to his vision of infinite spirit pervading the infinite universe. Ultimately, there is no specific difference between part and whole, and there is no number in the universe, for the universe is itself unity. And this is true whether we consider the mode of time, of space or of size. God  is in everything more intimately than its own form is in it, since He is the essence by which everything has its being. Diversity and Change express a unity embracing all formal multiplicity, for all is one in substance and in truth. Difference and numbers are not being, but are derived from being and surround being. "He who has found this Unity has discovered the indispensable key for the true contemplation of nature." 
Change is not toward a different being but toward a different mode of being; and the universe comprises all being and every mode of being:
Thus you will understand that all is in all but all is not totally and in every mode within each one....
Moreover, just as the soul (to use the usual expression) is in the whole form to which it giveth being, and is at the same time individual; and is thus similarly in the whole and in every individual part; so the essence of the universe is One in the infinite and in every part or member thereof so that the whole and every part become One in substance.... That which is said of the seed as regards the limbs of animals may similarly be said of food as regards chyle, blood, phlegm, flesh and seed ... and is similarly the case of all things, rising from the lowest grade of nature to the supreme highest thereof, from the physical universe known to philosophers to the height of the archetype in whom theologians believe ... until we reach an original and universal substance, identical throughout the whole, which is Being, the foundation of all kinds and of all forms -- just as in the carpenter's art there is a substance, wood, subject to all sizes and shapes but these are not wood, they are in, of, or around wood. Thus everything which maketh diversity of kinds, species, differences, properties, everything which dependeth on generation, corruption, alteration and change is not being or existence but is a condition and circumstance of being or existence which is one, infinite, immobile, subject, matter, life, soul, truth and good. 
When we aspire and strain to an origin and substance of things, we progress toward the indivisible, and we can never believe that we are united to the primal Being and universal substance until we understand indivisibility.... The Peripatetics and the Platonists reduce infinite indivisibles to one indivisible nature comprehending many kinds ... and many determinate kinds to one being which they reduce to a name and word, a logical abstraction and ultimately vanity. 
"The infinite dimension, being no magnitude, coincides with the individual." This is illustrated by geometric figures. Thus we are again brought to the coincidence of contraries. Contemplating the infinite One which lies behind all phenomenal manifestations, we recognize that
even in the two extremes of the scale of nature, we contemplate two principles which are one; two beings which are one; two contraries which are harmonious and the same. Therefore height is depth, the abyss is light unvisited, darkness is brilliant, the large is small, the confused is distinct, dispute is friendship, the divided is united, the atom is immensity.... Here are the signs and proofs whereby we see that contraries do truly concur; they are from a single origin and are in truth and substance one. This, having been seen mathematically is accepted physically.... Here as in a seed are contained and enfolded the manifold conclusions of natural science; here is the mosaic, the disposition and order of the speculative sciences. 
c. On the Infinite Universe and Worlds (De l'Infinito Universo et Mondi) 
The third of Bruno's philosophical works in the vernacular is the longest. Bruno himself tells us that it sees the birth of ideas inseminated in the work On Cause, Prime Origin and the One. In fact, while almost every idea in this work is foreshadowed in the two previous volumes, we have here the impression of the attainment of that joy in philosophic contemplation of which the author tells us and which we pray may indeed have sustained him through the awful sufferings which were ahead of him.
The speakers are Philotheo once more, Elpino, Fracastoro, Burchio, and Albertino. We have already hazarded the guess that Elpino may be Thomas Hill.  Girolamo Fracastoro of Verona is a historical figure whom we have already considered.  Burchio is less easy to identify. This person, persistently and arrogantly sceptical of the new message, is perhaps Thomas Bourchier, an English Franciscan educated at Oxford who was in Paris during Bruno's first visit, and had published there in 1582 both a Franciscan Martyrology and a Prayer for the Paris Convent addressed to the Minister General of the Order. Burchio is parallel to Gervasio in On Cause, Prime Origin and the One. Albertino appears in Dialogue V as "a learned person of a happier talent who, howbeit educated in the contrary doctrine, nevertheless by his power of judgement of that which he hath heard and seen, can distinguish between two disciplines and can easily alter and correct his views." We have already given reasons for identifying Albertino with Alberico Gentilis, the distinguished Italian refugee who was established at Oxford. 
The months in London had not abated Bruno's love for Mauvissière,  which in the Dedication to this work finds perhaps its most attractive expression. The Dedication suggests that Bruno is already beset with anxieties. In all his works the reader, almost overwhelmed by exaggerated verbiage, is apt to find himself suddenly held by a terse expression of the loftiest thought. Here we read, "It is Unity that doth enchant me. By her power I am free though thrall, happy in sorrow, rich in poverty, and quick even in death." This exaltation sustained Bruno at his moments of greatest suffering, and has held his memory in the hearts of succeeding generations who have struggled for truth and freedom. This quality we may suspect was the link between Mauvissière and Bruno.
The Arguments incorporated by Bruno in the Dedication are much longer than in the previous works. The reader may find it convenient to have a full analysis of this work. We shall summarize Bruno's own Arguments, supplementing from the Dialogues themselves.
Bruno presents a highly symmetrical scheme in the Argument of the first Dialogue. To the reader who has studied the Dialogue itself, it is clear that he is attempting to present a logical framework for the result of a complex psychological process comprising ecstatic vision and also aesthetic joy in the use of the mind. The first Dialogue, for example, is in fact not set forth in two parts and in numbered themes as in the Argument. Here is the content of Bruno's Argument to the first Dialogue:
Dialogue I, Part i 
Theme 1. Sense-perception must be interpreted by reason.
Theme 2. The universe is infinite. There is no proof of a boundary.
Theme 3. The universe is infinite because a finite world could not be self-contained and could not be imagined without position.
Theme 4. Quotes Lucretius: "If the universe is finite, what is beyond?"
Theme 5. The difficulty of defining position of a finite world in infinite space.
Theme 6. A finite universe requires the conception of a Void.
Theme 8. Sense-perception suggests rather than denies infinity (quoting Lucretius); so does reason.
Theme 9. Infinite space is the only possible conception to our minds, and can only be denied verbally, not with our thought.
Theme 10. "It is well" that this world exists -- therefore also that an infinity of other worlds exists.
Theme 11. The virtue [Bonta] of this world cannot be communicated to another world.
Theme 12. Since we accept individual all-embracing infinity [i.e., God], no reason and no sense-perception will fail to admit also corporeal and extended infinity.
Theme 13. Our little surrounding space is as nothing to infinity and can have no relation to it; but as "it is well" that our space exists, so also is it for countless others.
Theme 14. Infinite power must act on the infinite, on infinite corporeal being.
Theme 15. Only an infinite universe can comprehend all perfection.
Theme 16 [partially repeating Theme 14]. Infinite Efficient Cause must produce infinite Effect.
Theme 17. An infinite universe is satisfying to our mind and the contrary brings difficulties and inconveniences and we repeat Themes 2 and 3.
Theme 18. If our universe be spherical, then the space beyond it which adjoins it must also be spherical.
Theme 19. Elaborates the discussion of Theme 2.
Theme 20. Elaborates the discussion of Theme 10.
The passive power of the universe having been discussed in Part i of the first Dialogue, Part ii turns to the active power of the Efficient Cause.
Dialogue I, Part ii
Theme 1. Divine power should not be otiose -- and a finite Effect would be no less otiose than none.
Theme 2. To assert that divinity has not created the infinite is to deny divine goodness and greatness, while the contrary view is in no way contrary to theology.
Theme 4. Aristotelians, in supposing a finite world, are really accusing Omnipotence of lack of will and of lack of power.
Theme 5. If Omnipotence does not create the universe infinite, then it cannot do so: and if it cannot create it infinite, then also it cannot preserve the universe to eternity. For if finite in one respect [Space], the universe must be finite in every other respect [Time]. For in it, every mode is an object; and every object and mode are one and the same.
Theme 6. The converse of I, i, 10 [if "it is well" that the world exists, then "it is well" that an infinity of other worlds exist]. Shows why theologians defend the contrary view [because of the people's limited understanding and wrong use of knowledge]. The friendship between learned theologians and learned philosophers.
Theme 7. Distinguishes active power from individual actions; and expounds infinite power "better than theologians have ever done."
Theme 8. The motion of the infinite worlds is not by constraint but according to the inner nature of each; and yet an infinite motor force exists.
Theme 9. Infinite motion can be verified in each world. And, because each world moves itself and is moved at the same time, therefore each world can be seen in every point of the circle that it describes around its own centre -- and this difficulty we will solve later in more detail.
We now turn to the Dialogue itself. In the opening lines of the first Part, each speaker displays his dramatic function. Philotheo propounds the new doctrine; Elpino is the enquirer, incredulous but not pertinacious in error; Fracastoro is the man of judgement who will give attention and appraise the speakers; while Burchio is merely frivolous in his ignorance. Albertino, the second enlightened convert, does not appear until the fifth and last Dialogue.
The first Part of the first Dialogue leads at once to the heart of the subject. The universe is infinite, the worlds therein are innumerable, the infinite First Cause is both transcendent and immanent; the infinite universe and all its parts move in conformity with their own nature, which is the creation of the Omnipotent First Cause, and thus are reconciled both Free Will and Necessity. I, i, Theme 1 culminates:
Wherefore truth is in but very small degree derived from the senses as from a frail origin, and doth by no means reside in the senses ... but in the sensible object as in a mirror; in reason, by process of Argument and discussion; in the intellect, either through origin or by conclusion; in the mind, in its proper and vital form.
Philotheo proceeds to refute Aristotelian arguments. I, i, Themes 3, 4 and 5 are taken together. There follow I, i, Themes 6 and 7, and the Aristotelian view is stigmatized as "mere words and excuses." We pass to I, i, Themes 8 and 9 and we are reminded, "Divinity hath not as aim to fill space, nor therefore doth it by any means appertain to the nature of divinity that it should be the boundary of a body (cf. I, ii, Themes 2, 4, etc.) and "that which containeth is eternally different from that which is contained." I, i, Theme 10 is introduced by a consideration of the "aptness" of single infinite space to receive an infinity of worlds. Fracastoro points out that the existence of Void beyond our universe is inconceivable by us, so that we are forced to accept an infinite Plenum. Fracastoro's acceptance of these views signalizes also the beginning of Elpino's conversion, and in the succeeding discussions Elpino finds himself reluctantly accepting more and more of the new view.
I, i, Themes 12-17 are set forth by Philotheo and are fully accepted by both Fracastoro and Elpino. This latter expands several of the themes already discussed, emphasizes I, i, Theme 17 and expounds I, i, 18-20. He is complimented by Fracastoro and then introduces Part ii of the first Dialogue by a question concerning the relation between infinite Cause and infinite Effect. The theme has been adumbrated by Bruno in the work On Cause, Prime Origin and the One. Once more Philotheo expounds his vision of infinite action and infinite passion, recapitulating the earlier themes, emphasizing I, ii, 1-2. He passes to I, ii, Theme 3, the distinction between the "explicit though not the all-comprehensive totality of the infinite universe" and the "whole comprehension and complete totality of the Creator," using arguments reminiscent of Cusanus.  I, ii, Theme 1 is next expanded in I, ii, Themes 4-5. Fracastoro avers that the coexistence of infinite active power and infinite passive power provides the clue whereby "we perceive the complete identity of Liberty, Free Will and Necessity, and moreover recognize that Action and Will, Potentiality and Being are but one." The second part of I, ii, 5, as given in the Argument, is hardly explicit in the text, but we are told, "He who denieth infinite result denieth also infinite power."
Passing to I, ii, Theme 6, Fracastoro declares that there is no real difference between theologians and philosophers. Philotheo expounds I, ii, Theme 7, answering Elpino's faint surviving difficulties, and passes to a magnificent declaration of faith in the view presented by I, ii, Theme 8. This is denied by Elpino, who prefers "the glorious and presupposed foundation that the Best and Greatest doth move the whole. Nevertheless," he continues, avowing agreement as he presents the very marrow of Bruno's philosophy, "as regards that which you are wont to say concerning the soul of the world and concerning the divine essence which is all in all, filleth all, and is more intrinsically pervasive of things than is their very own essence, because it is the essence of essences, the life of lives, the soul of souls"; yet Elpino is still worried because "it doth none the less appear to me that we may say that 'He moveth all things rather than that He bestoweth on all things the power to move themselves.'" So in I, ii, Theme 9, Philotheo again expounds his synthesis of Necessity and Free Will, of Transcendent and Immanent Divinity, and shows them all exemplified in the complex motions of our earth (for which he uses a geometric figure already given in The Ash Wednesday Supper). Elpino accepts the statement and asks for further instruction at another meeting on which the speakers agree.
The second Dialogue is again concerned with the relationship between infinite first cause and the infinite created universe. Certain of Aristotle's general views of matter and space, incompatible with the infinite universe, are considered and confuted. Elpino presents the Aristotelian view mainly from the fourth and eighth books of the Physica. 
The following is the gist of Bruno's Argument to the second Dialogue:
(ii). Our imagination should not be able to aspire Beyond Divine Action.
(iii). Indifference of the distinction between Divine-Intellect and Divine Action.
(iv). If the corporeal quality perceptible to our sense is endowed with infinite active power, then what will be the absolute totality of active and passive power inherent in the totality of all things?
Theme 2. A corporeal object cannot be terminated by an incorporeal object, but either by a Void or by a Plenum.
In either case, beyond the world is space, which is as matter and has the same passive power. Refutation of Aristotle's view of the incompatibility of dimensions [i.e., Aristotle's denial of the identity of matter and space].
Theme 3. Distinction between the world [or finite universe as imagined by the Aristotelians] and the single infinite or comprehensive universe.
Theme 4. Elpino brings forward Aristotle's views seriatim and they are confuted by Philotheo. They concern both simple and compound bodies.
The vanity is shewn of six arguments concerning "motion which cannot be infinite" and other similar propositions. The reasons are shewn for change and termination of motion and for strong and weak impulses: It is demonstrated that an infinite body can be neither heavy nor light, and Aristotle's arguments in De coelo et mundo and from the third book of the Physica are each in turn confuted.
Thus the second Dialogue opens with further consideration of the infinite first cause.
II, Theme 2 leads to a consideration of the nature of position, space and the void.
After expounding II, Theme 3, Philotheo invites Elpino to put forward the opinions of Aristotle on these matters in turn (II, Theme 4). Elpino follows very closely the reasoning in De coelo. He presents a program of arguments: Can there be a simple body of infinite size? This is impossible for either (i) bodies of circular or (ii-vi) bodies of any other shape. Clearly, therefore, there can also be no composite body of infinite size. II, Theme 4, i is a geometrical argument based on the motion of a radius of an infinite circle. Philotheo replies that "never has one been found so barbarous and so ignorant as to have posited the infinite world, and to have attributed motion to it." Elpino agrees that all Aristotle's six arguments depend on the false assumption that his adversaries attribute motion to an infinite universe. The five last reasons suppose motion in a straight line and are based on the qualities of lightness and heaviness. Philotheo proceeds to enunciate, in phrases that might be from Cusanus (who is, however, not mentioned), the attributes of an infinite universe.  Bruno gives a modification of the doctrine of the elements:
No infinite body is either heavy or light. For these qualities belong to parts in so far as they tend toward their own whole.... Thus on our earth the particles of fire seeking to escape and mount toward the sun, carry ever with them some particles both of earth and of water with which they are conjoined; and these becoming increased do thus by their own natural impulse return to their own place ... wherefore the earth in her own space is no heavier than the sun in his space or than Saturn or the North star in their own.
Aristotle's arguments concerning the parts of an infinite body are analyzed and refuted with some repetition of former matter and with a fine exposition of cosmic metabolism.
Philotheo resolves the difficulty of finite parts within a single infinity and discusses the arguments in the De coelo concerning motion of the parts and of the whole. To the Aristotelian arguments that the infinite cannot be agent or patient in regard to the finite, nor can an infinite body act on another infinite body, Philotheo replies that while he agrees with these theses, they do not affect the issue, since there can be no numerical relation between the parts and the infinite whole, nor between finite time and eternity. Moreover, whatever arguments to the contrary Aristotle may adduce, "this inference is not physically valid though logically it may be correct."
Philotheo's views are illustrated by geometrical demonstration and lead to the conclusion that "if two infinite contraries be opposed, either a finite change or none at all will come to pass" and that when two contraries are opposed, there ensues finite action and finite alteration.
We have now recapitulation. Philotheo again expresses his exalted vision of infinity. He derides the assumptions of the Aristotelian cosmology and affirms the relativity of all sense-perceptions. Elpino shows the completeness of his conversion by repeating the views of Philotheo and the rejection of the Aristotelian opinions.
The following is the gist of Bruno's Argument to the third Dialogue:
Theme 1. Aristotle's heaven and spheres are again denied, since heaven is a single general space embracing infinite worlds. The Aristotelian view is an illusion created by sense-perceptions.
Theme 2. The motions of the heavenly bodies are also illusory sense-percepts.
Theme 3. All celestial bodies have motion. The suns, in which fire predominates, have different motion to that of the earth, in which water predominates. Thus too some stars shine by themselves like suns, some by reflection like earths.
Theme 4. Stars at vast distances may yet be heated by our sun, and distance explains the presence or absence of scintillation.
Theme 5. Cusanus is cited concerning the material and habitability of other worlds and concerning the cause of light.
Theme 6. No body appears light when viewed from itself.
Theme 7. "Quintessences" and the Aristotelian series of spheres are denied.
Theme 8. Distinction between the four elements is accepted, but not the Aristotelian order of the elements. The worlds are heterogeneous bodies, animate globes in which earth is no heavier than the other elements.
The movement of particles within each globe is likened to the movement of the fluids in the animal body.
The earth herself is without weight. Moreover the unifying body is not earth but water.
Theme 9. Concerns the nature of the animate globes and their inhabitants.
Theme 10. A gibe against the opponents of the new views.
The third Dialogue opens with a lyrical speech by Philotheo unfolding a view of the whole universe as One. "Immense and infinite is the complex of this space and of all the bodies contained therein." Later Philotheo bursts into a charming little sonnet on the endless motion of the earth and of all other bodies. The theory is propounded that stars more distant from the sun can nevertheless be heated by it as a result of their larger orbit and slower revolution, combined with a more rapid spin.
The Dialogue is very largely a recapitulation of the earlier two, and is well epitomized by Bruno's Argument. Elpino's conversion being now achieved, his questions are merely links between the speeches of the others, or occasionally he is himself the mouthpiece of a reiteration of Philotheo's views. The obstinacy in error of Burchio introduces occasional comic relief. After the end of this Dialogue, Burchio fades from the scene.
Bruno's Argument to the fourth Dialogue gives the main contents of the Dialogue under numbered headings which again are not in the text itself:
Theme 1. Recapitulation concerning the form of the universe with its infinity of worlds.
Theme 2. Recapitulation refuting arguments against the infinite bulk or size of the universe (discussed in the first Dialogue). Aristotle's arguments against an infinite multitude of worlds are refuted:
(i). on general principles;
(ii). by consideration as to the nature of heaviness and lightness with special regard to the hindrances to motion of heterogeneous parts from one to another earth.
Theme 3. Why celestial bodies are not close to one another nor can be close to a void.
Theme 4. Considerations of local space and of the behaviour to be expected of a stone equidistant between two worlds.
Theme 5. Aristotle's error in supposing a force of heaviness or lightness [of elements] attracting one body to another. The true cause of the universal tendency to resist change, a tendency which "causeth flight and persecution."
Theme 6. Motion in a straight line appertains not to worlds but to parts thereof which, if not too distant, tend to approach one another.
Theme 7. The behaviour of comets shows the error of Aristotle in supposing that a heavy body necessarily suffers attraction by its natural containing body, however distant.
Theme 8. Simple bodies of identical nature in innumerable diverse worlds have similar motion. "Arithmetical diversity" causes difference of locality, each part having his own centre and a common centre which is not the centre of the universe.
Theme 9. Bodies have no determined upper or lower portion, but have a natural direction of their conversation.
Theme 10. Motion is infinite.
A moving body tends toward infinity and to the formation of innumerable compounds. But neither heaviness nor lightness nor infinite speed follow: and motion of adjacent parts, so far as they preserve their own nature, cannot be infinite. Attraction of parts to their own containing body happens only within their local space.
The fourth Dialogue gives further recapitulation in the form of question and answer by Elpino and Philotheo with occasional comment by Fracastoro. Elpino, though he voices the Aristotelian objections, shows himself now convinced and sometimes takes up the exposition of the new view. The discussion is again based on the De coelo of Aristotle.
The discussion in the fourth Dialogue ranges over the themes of the single all-embracing infinite universe, the infinity of worlds and the behaviour of the diverse matter and the particles that build up our world and all other worlds with a fine presentation of cosmic metabolism and of the eternal process of decay and regeneration. Philotheo observes, "Throughout the ethereal field, heat and cold, diffused from the bodies wherein they predominate, gradually mingle and modify one another to varied extent, so as to become the approximate origin of the innumerable forms and species of being." It is in this Dialogue that Philotheo mentions the plastic surgery which was arousing such interest in Italy during Bruno's boyhood.  Theme 4 is illustrated vividly by observation of the behaviour of a spreading fire. At the close of the Dialogue, Elpino promises that at their next meeting the Aristotelian views shall be well represented by Albertino.
The fifth and last Dialogue introduces Albertino, brought up in the old views but able to appraise and accept the new. Albertino brings forward twelve reasons against the opinions of Philotheo. Each in turn is confuted to his ultimate satisfaction. Bruno's argument is somewhat discursive and the best survey of the fifth Dialogue is obtained by giving (not from the Argument, but from the Dialogue itself) each of Albertino's twelve (or rather thirteen)  theses with the reply to each. They are as follows:
Thesis 1. Beyond our universe neither time nor space exists.
Answer 1. Beyond the imagined convex circumferences of the universe is time.
Thesis 2. There is one primum mobile; therefore there is one world.
Answer 2. Truly there is One -- for all reduce to a single utterly simple and indivisible principle which is truth and being.
Thesis 3. We may deduce only one world from the positions occupied by bodies in motion.
Answer 3. There is no "natural position" and no innate heaviness or lightness. The same argument is enlarged in a diversion as to the similarity of our earth and the other celestial bodies.
Thesis 4. If there be many worlds, the centre of one will be nearer to its [elementally contrary] circumference than to the [elementally] kindred centre of another sphere.
Answer 4. Particles are not necessarily related to any centre except that of their own globe. Moreover, contraries are not necessarily at the furthest distance apart, since one may influence the other. Further, the four elements are intimately mixed in the various particles -- and water is mixed with every part of our earth. And if the elements are to be arranged by qualities, water [instead of earth which is heaviest] must occupy the central position, if fire, which is lightest, is at the circumference: since water, which is cold and moist, is in both those qualities most opposed to fire.
Thesis 5. Similar to 4. If six circles are ranged round a seventh, the heavy element in the centre of one circle is nearer to the circumference of another than to the centre of that other.
Thesis 6. Similar argument to Thesis 5, as regards the interspheric triangles in the figure of Thesis 5.
Answer to 5 and 6. All these petty difficulties disappear when we realize that the universe is One.
Thesis 7. If there are other worlds they must either (i) be infinite, which is for many reasons impossible, or (ii) be finite, in which case there must be a definite number. If so, why just this number? Why not a single one?
Answer 7. There is but one universe with innumerable worlds. Quotation from Lucretius, De rer. nat., II, 1040-51.
Thesis 8.  Nature shuns superfluity [sic!]. She encloses herself in the smallest compass.
Answer 8. Against this thesis Philotheo quotes Lucretius, De rer. nat., II, 1052-57, 1064-66, that seeds unnumbered on every side and with everlasting motion are driven in all directions. Therefore there must be a plurality of worlds.
Thesis 9.  It does not necessarily follow that because God can create more worlds, therefore they necessarily exist. There may not be the passive power to be created.
Answer 9. The argument that active power is limited in action by the limitation of passive power is a contradiction in terms. Lucretius is again quoted as to the certainty of a plurality of worlds and as to the behaviour of the seeds of things (De rer. nat., II, 1067-76).
Thesis 10.  A plurality of worlds would be unreasonable, for civil intercourse between them would be impossible, and this would be a reflection on the gods who created them.
Answer 10. Such civil intercourse would be unnecessary and harmful. It is much better that living creatures should be dispersed. Quotation from Seneca, Medea (w. 335-39) as to the harmful result of uniting lands by seafaring.
Thesis 10. bis.  Plurality of worlds is a thoroughly unpractical plan. The spheres would hinder one another's motion.
Answer 10. bis. In fact they do not collide but pursue their courses in comfort.
Answer 11. Multiplication is by mere vigour of nature.
Thesis 12. The world is perfect. Therefore there is nothing to be added to it.
Answer 12. Plurality is not needed for the perfection of any of the single worlds, but for the perfection of the universe.
All the answers are given by Philotheo (except for one little shot from Elpino). Then Albertino bursts into a paean of admiration and praise for Philotheo, prophesies his future vindication and begs him to continue expounding the glorious truths concerning the infinite universe.