Giordano Bruno: His Life and Thought
LAST WANDERINGS: THE GREAT
LATIN POEMS AND OTHER
a. Bruno's Second Sojourn in Paris (1585-86)
THE recall of Mauvissière to Paris at the end of 1585 brought an abrupt end to Bruno's sojourn in London. It is not easy to follow why Mauvissière was recalled or why payments had ceased to reach him in London. His financial embarrassments were increased by the failure of Mary Queen of Scots to repay large sums of money which he had lent to her. Moreover, a letter from him has come down to us describing the disastrous robbery of all his personal possessions during the voyage back from England.  The last years of his life were saddened by the ill-health of his wife and then by her death in childbirth a year after they left England. After his return to Paris, Mauvissière was employed in command of armies both under Henry III and Henry IV. He died in 1592, the year in which Bruno passed from the world to the eight years of his martyrdom.
On their arrival in Paris toward the close of the year 1585, Mauvissière was in no position to offer hospitality. But Bruno seldom failed to attract round him a group of cultured persons fascinated by his talk, and he stated to the Venice Tribunal that he lived in Paris "in the house of gentlemen of my acquaintance, but mostly at my own expense." It appears that he lodged near the College of Cambrai where he may have found congenial acquaintances.
Bruno during this period made a great effort toward reconciliation with the Church. He described at the Venice trial how he first approached the Bishop of Bergamo, the Papal Nuncio in Paris. Armed with an introduction from Mendoza, whom he had known as Spanish Ambassador in England, Bruno begged the Bishop to intercede for him with Pope Sixtus V. He also invoked a Jesuit Father, Alonso Spagnolo. But both the Bishop and Spagnolo refused to attempt to secure Bruno's absolution and admission to the Mass unless he would return to his Order, and this Bruno would not contemplate. 
Three volumes from Bruno's pen appeared in Paris in 1586, the year after his arrival from England, all from the same publisher. The first of these is entitled A Figure of the Aristotelian Physical Teaching. The first part illustrates the application of Bruno's mnemonic system and his use of figures, for it gives instructions for memorizing the contents of the eight books of the Physica. It is dedicated to the Abbot Pierre Dalbène of Belleville.  But to interpret these instructions requires an expert in the Art! There follow two paragraphs: "The Division of Universal Philosophy" (according to Aristotle); and Aristotle's "Division of Natural Philosophy." Eight works or groups of writings by Aristotle on "Natural Philosophy" are enumerated.  The second half of the little volume gives an epitome of the eight books of the Physica. It shows signs of having been printed in haste and not fully completed.
Bruno's mind was also running on mathematics. He met in Paris Fabrizio Mordente of Salerno who wrote on Integration and had also invented the eight-pointed compass.  As though he had not enough troubles of his own, Bruno found himself overwhelmed with indignation at the neglect of this mathematician's work and especially of his eight-pointed compass. Bruno now issued in Paris a volume Concerning the Almost Divine Invention by Fabrizio Mordente of Salerno for the Perfect Practice of Cosmic Measurement. After a paean of praise to the shamefully neglected Mordente, Bruno describes and figures the instrument in two Dialogues. He appends to the volume a "Dream" (Insomnium) in which he figures an astronomical device for ascertaining the position and the motion of heavenly bodies. Bruno declares that he cannot remember the face or the habit of the inventor of the method, who, however, described it in the "Dream" so that it has remained vividly in his mind. 
By a happy chance, one of those who met Bruno at this time in Paris has recorded his impressions. The diarist was Guillaume Cotin, librarian of the Abbey of St. Victor.  He first mentions Bruno as visiting his library on the 6th December, 1585. Bruno was back on the following day, and on the 12th December he brought his own works on the art of memory to show to the librarian. Two more visits are recorded in December -- and then a final visit early in February. We may imagine that a friendship sprang up between the two men, as many details of Bruno's early life are recorded by Cotin, as well as notes on Bruno's published and unpublished works.
It is clear that the pious librarian of St. Victor was at first fascinated by his visitor. He refers to the inquisitors who threatened Bruno at Rome in 1576 as "ignorant and not understanding his philosophy."  He cites Bruno's views and speaks of his writings. We hear that "Jordanus told me that Fabricius Mordentius Salernitanus is in Paris, aged 60, a god among geometers ... yet knowing no Latin. Jordanus will print a Latin account of his works."  Cotin quotes Bruno's opinions also of the scholars and preachers of the day. A certain Hebrew convert seems to have been alone among preachers in winning Bruno's admiration both for his learning and his eloquence. Another preacher, Bossulus, was praised only for eloquence and clear pronunciation.  Bruno was for the most part a biting critic. He expressed his contempt for Toletus  and the Jesuits who were preaching in Italy.
There ensued an estrangement between Bruno and the librarian. Though both remained in Paris for some four months longer, no further visits are recorded. Moreover, in March 1586, Cotin is listening to an unfriendly account of Bruno's humiliation at Geneva seven years previously. In May he reports dryly and without comment the disastrous affair at the College of Cambrai which must now be recounted.
In Pentecost week of 1586, Bruno boldly challenged all and sundry to impugn the One Hundred and Twenty Articles on Nature and the World sustained against the Peripatetics by his pupil John Hennequin.  It seemed that his challenge would be left unanswered. But at the last moment there arose to reply a young advocate, Raoul Callier. This young man was a close relative of Nicolas Rapin of Fontenay in Poitou, notorious for his harsh treatment of Huguenots. At his death-bed confession, strangely reported in full by the priestly Father who officiated, Rapin declared that "The only good thing that he remembered to have done since his youth was that he prevented the public teaching of atheism ... in Paris."  Had Rapin assisted Callier or intervened against Bruno during or after the disputation? We cannot tell, but we may well believe that with such affiliations, Callier applied himself to his task with zest. He spoke with such effect that the students, ignoring Hennequin, set upon Bruno and demanded that he should either reply or retract his calumnies against Aristotle. Bruno undertook to reply on the following day, when, however, the proceedings again opened with an oration by the brilliant young Callier. "Hennequin could reply only to the first argument," records Cotin. Bruno was then called to speak, but he declared, so runs the diarist's report, that the hour was too late. Nor would he appear on the following day, "saying that he was already vanquished." The One Hundred and Twenty Articles were, however, published while Bruno was still in Paris. The copy in the British Museum is believed to be the sole survivor of the edition. The volume bears a dedicatory inscription to King Henry III, and one to Jean Filesac, Rector of Paris University.  But this was the end of Bruno's second visit to Paris. Once more he resumed his wanderings. "Because of the tumults," he stated to the Inquisitors at Venice, "I left Paris and went to Germany." 
b. Marburg and Wittenberg (1586-88)
Taking up his wanderings once more, Bruno passed through Mainz and Wiesbaden where, as he related to the Venice Tribunal, he could find no livelihood. He came to Marburg, and on 25th July, 1586, he matriculated in the university there. After his name on the matriculation roll, "Iordanus Nolanus Neapolitanus, theologiae doctor romanensis," the newly elected Rector has recorded the events which brought Bruno's sojourn to a precipitate close:
When the right publicly to teach philosophy was denied him by me for good cause and with the assent of the philosophical Faculty, he burnt with rage, and impudently reviled me in my own house as though I had acted in defiance of the law of nations, against the custom of all German universities and contrary to all schools of the humanities. Wherefore he declared that he had no wish to remain a member of the Academy. So his fee was readily returned to him, and he was discharged from the register of the university.
The Rector's action appears nevertheless not to have been unanimously supported by his colleagues: Spampanato, who viewed the Register, points out that, whereas the original inscription of Bruno's name was crossed through by the Rector, the letters remained legible, but that the words, "with the accord of the Faculty," had been completely obliterated by a later hand. 
But Bruno resumed his wanderings, and at length he reached a temporary haven at Wittenberg in Saxony, where he found his compatriot, the jurist Alberico Gentilis, of whom we have already had a glimpse in Oxford.  Gentilis, he relates, obtained an invitation for him to lecture on the Organon, which resulted in his being engaged to lecture for the next two years. Three new works were published by Bruno during this breathing space: two volumes published in 1587, and his speech of 1588, expressing his thanks and farewell to the university.  In addition, an enlarged edition of the One Hundred and Twenty Articles against Aristotle appeared at Wittenberg under the cryptic title of Camoeracensis acrotismus, which we may perhaps render The Abruptly Ended Discourse in the College of France.  The volume bears, prefixed to the Dedications to Henry III and to Filesac, a new Dedication to the "Philosophers of Paris and to other philosophers in the generous realm of Gaul who are friends and defenders of the dogmas of a wiser philosophy."
The first of the Wittenberg volumes bears a cumbrous title which we may epitomize as: On the Synthetic Lullian Lamp leading to infinite propositions ... to the understanding of all things ... the sole Key to all Lullian works and no less to Pythagorean and Cabbalistic mysteries.  Bruno was never niggard of gratitude and the long Preface to the Rector  and Senate of Wittenberg University expresses heartfelt thanks for the benevolence and hospitality extended to him,
a person of no name, fame or value among you, supported by no prince's praise, distinguished by no outward trappings such as the vulgar are wont to admire, a fugitive from the Gallic tumults; nor was I examined or interrogated on your religious dogma, with that custom of harsh discipline of perfidious barbarians, violators of the laws of nations, to whom should be closed that heaven and earth which they either entirely deny as a common and social possession ordained by nature for all men, or concede them only with impious and deadly calculation.
As Bruno expatiates on the humanity of his hosts, their urbanity, true benignity, and devotion to the Muses, "whereby he recognizes truly a university," we catch the same accents with which he saluted his beloved friend Mauvissière who had similarly extended to him the priceless benefit of leisure and freedom for thought and study. He used his leisure, studying Eriugena, Cusanus, Paracelsus, his hero Raymond Lull, "already commented by Cornelius Agrippa," the humanists Lefèvre of Etaples and de Bovelles,  at whose works we have already glanced, and many other writers of East and West. Each of the faculty of that great university he mentions with affection and admiration, not omitting the Chancellor and the Rector. Once more we recognize the transparent honesty of Bruno's passion to learn and to know. The Lullian Art which he would set forth in honour of these men is no less than the whole Art of Thought expounded in the Lullian manner with the aid of geometric figures, concentric circles and tables.
The second Wittenberg volume treats Of the Advance and Enlightening Hunt for Logic and is in a somewhat similar vein, inspired by Lullian methods. It is dedicated to George Mylius, Chancellor of Wittenberg University. 
A further work has come down to us from the sojourn at Wittenberg, though never published by Bruno. This is The Art of Peroration Delivered by Jordano Bruno, the Italian of Nola, Communicated by Johann-Henricus Alstedius for the Benefit of Those Who Wish to Know the Force and Method of Eloquence, which was published in 1612, long after his death, by the house of Antonius Hummius in Frankfurt.  In the Dedication to "his most noble and learned patron" Count Abraham Wrsotzky Gorni of Poland, Alstedt recalls the talk they had both enjoyed with Count Vladislaus ab Ostrorog, and records his admiration and love for Count Wrsotzky Gorni. He states that the book has been in his hands for two years and that he has edited and corrected any suspected errors, taking care to change the work of Bruno as little as possible:
For no one will seek here for elegance of style or mere entertainment, since neither of these was the author's purpose. Had I wished to make from this a new treatise, verily it would have emerged more elegant. But I preferred to communicate to the studious the doctrine delivered in his own style by the author, a man indeed not without erudition, rather than to concoct a new treatise ... I have striven to produce the same form as in the "Canonical Triads" which, Sir Count, I dedicated to you, that these two books may unite to testify to the philosophy and the Christianity that was with the three of us.
Alstedt dates his Dedication from Herborn in Nassau, May, 1612. The sub-title of the volume is Introduction to the work on Rhetoric of Jordano Bruno the Nolan from Italy. In an Introduction to the Reader, Alstedt gives an epitome of the two Parts of the work. This Introduction ends with a Table of the logical method for oratory prescribed by Bruno. Part I is entitled: Explanation of the Work on Rhetoric Sent by Aristotle to Alexander, Privately Dictated by Jordano Bruno the Italian of Nola at Wittenberg in 1587. Part II is entitled The Art of Rhetoric, and gives elaborate schemes for the construction of an oration, with sundry alternatives, synonyms, etc., illustrated by elaborate diagrams.
There have come down to us in manuscript from this period two other works by Bruno on Lullian mnemonics and another commentary on the Physics of Aristotle. None of these reached publication under his own supervision. 
But once more the course of political events brought to an abrupt end Bruno's respite of quiet study and teaching. His exposition to the Venice Tribunal is somewhat confused, but it is apparent that the death of the aged Elector Augustus (Bruno calls him Duke) in February 1586, and the accession of Christian I, had brought disturbance and a shift of power from Lutherans to Calvinists.  The latter were not disposed to harbour Bruno, and ultimately he had to leave. His Valedictory Oration to the Rector, professors, and to his noble and learned audience at the university is full of praise for his hosts, though a less peaceful situation is perhaps indicated by the cloudy complexity of his mythological analogies.  We know that he was forced to salute and depart. Perhaps he had hardly expected an extension of peaceful life.
Two documents from the Wittenberg period bear witness to his saddened outlook. One is the Family Album of Hans von Warnsdorf of Wittenberg,  and the other is a print portraying the Siege of Nola by the troops of Hannibal.  On each are inscribed under the caption Salomon et Pythagoras these lines from Ecclesiastes, a work we have seen already haunting Bruno in his early days in Paris:
Quid est quod est? Ipsum quod fuit.
The date inscribed in the Warnsdorf Album is "Wittenberg, 18 Sept." It must have been written in 1587. The print bears the date 9th March, 1588.
c. Prague and Helmstedt (1588-90)
In 1588 the changeless rhythm of Bruno's life was renewed, and he passed to the imperial town of Prague to the Court of Rudolph II, where again he found a friend, the mathematician Fabricius Mordentius of Salerno. 
He immediately published a brief new work, A Scrutiny of the Lullian Categories, to which he appended a reprint of The Synthetic Lullian Lamp, published the year before at Wittenberg. The whole new volume  was dedicated under the date 10th June, 1588, to William San Clemente, Ambassador from the King of Spain to the Emperor. This statesman, we gather from the Dedication, had, like King Henry III of France, fallen under the spell of Bruno's expositions of Lull's methods of logical thought and of memory. The two works in the present volume will, the author promises, afford to his patron's talent a complete understanding of the Lullian Art. The latter work, he explains, is not so much to give the ordinary principles of medicine as to shew that the general Lullian Art applies to all sciences and faculties whereby anyone may acquire knowledge of real medicine. A few pages, partly in Bruno's own hand containing a tract On Lullian Medicine are referred to this period. From Bruno's hand too we have a later version of a figure illustrating his Commentary on the Physics of Aristotle (p. 143) as well as some alchemical recipes, and perhaps also a Mnemonic table found with these. 
Soon Bruno presented to the Emperor himself a volume on the Principles and Elements of Geometry. It comprises One hundred and sixty Articles against the Mathematicians and Philosophers of this age; one hundred and eighty Exercises, for the solution by a possible and easy method of one hundred and eighty Problems, some hard, some indeed impossible by any other method.  In his Dedication he declares that he would be unworthy of the light vouchsafed to him if he did not try to illuminate also other men. While the form of the work borrows from Euclid's Elements, the very first axioms warn us that we are in a non-Euclidean universe. "The Universe is the maximum.... The individual is the minimum, neither perfect nor imperfect, the universal measure..." and we soon reach symbolism for Mind, Intellect, Love.
Such symbolism has many parallels in the literature of the period. In the ensuing pages are many elaborate figures, some using Hebrew script. We may not be surprised that the Emperor Rudolph II, rewarding the writer with three hundred talari,  issued no invitation for his further sojourn in Prague. So within six months of his arrival, Bruno fared forth, this time northward again, to the newly founded Julia Academy of Helmstedt in Brunswick, where he was able to live for a year on the Emperor's gift.
His only publication in 1589 was the Consolatory Oration which he was honoured to make to the university on the 1st July on the death of the Founder, the beloved Duke Julius, which had taken place in the previous May. 
The oration is a somewhat extraordinary document. For Bruno not only expresses his customary gratitude for a quiet haven of study, but in describing the disturbances and woes of the rest of Europe, permits himself the bitterest strictures on his own land. "Spain and Italy," he declares, "are crushed by the feet of the vile priests." He contrasts the free pursuit of study at Helmstedt with the tyranny and greed that pervaded his own land. Yet, at Helmstedt we know that Bruno's path was not entirely smooth. For there has survived a document dated 6th October, 1589, bearing Bruno's signature and addressed to the Pro-Rector of the University of Helmstedt: 
Jordanus Brunus the Nolan, excommunicated in public assembly but without a hearing by the Chief Pastor and Superintendent of the Church in Helmstedt -- who acted both as judge and executioner -- appeals to the Pro-Rector and ... Senate, humbly protesting against the public execution of this private and most unjust sentence: he pleads to be heard so that should judgement fall upon his rank and good name, he shall at least know that it has fallen justly....
The matter is somewhat obscure, since it is fairly certain that Bruno never formally joined the Protestants, and therefore could not have been excommunicated by them. Moreover, no record survives of the result of his appeal. Perhaps this episode explains why none of his works except the almost official Consolatory Oration was published at Helmstedt. Possibly at this time Bruno made a brief visit to Frankfurt. For the Italian bookseller Brictanus, called to give evidence at Bruno's Venice trial in May 1592, stated that he had first met him "at Frankfurt some three years ago." But the winter 1589-90 must have been passed by Bruno at Helmstedt. He stated at the Venice trial that he left the town equipped with eighty scudi given to him by the young Duke as a reward for his oration, and he set forth for Frankfurt, the emporium of books, to arrange for the printing of his great Latin philosophical works, in combined verse and prose. These we shall examine presently.
Two letters from Jerome Besler of Nuremberg (1566-1632), a friend and secretary of Bruno, give an interesting glimpse of the last days of Bruno before starting for Frankfurt.  Besler had matriculated at Helmstedt in November 1589,  and Bruno had employed him as secretary during the winter 1589-90. He came of a family of some learning, his father having been the first Protestant pastor of Sprottau in Silesia. His name appears in the Venice trial as a pupil of Bruno who acted as his scribe again in the last months at Padua. Besler had meanwhile turned to the study of medicine, in which he graduated at Basle in 1592. He settled in his native town where he became a physician of some eminence, and among his pupils was his brother Basil the botanist (born in 1561) and his son Michael Robert (1607-1661), author of several medical works. But his long life brought Jerome no episode so important as his association with Bruno. The two letters from Helmstedt are dated respectively the 15th April and 22nd April, 1590, and are addressed to Besler's uncle, the physician Wolfgang Zeileisen. In the first letter Besler describes having gone with Bruno to Wolfenbüttel to claim fifty florins promised him by the Prince, "a thing marvellous and unexpected." A few days later Bruno had intervened in a disputation. He was working hard, and soon handed Besler a new tract on The Inventive Art (of Lull), then one On Medicine, and again one on The Lullian Art. If occasion should offer to print a work in Magdeburg and thus to give pleasure to the Prince, Bruno would stay in that town. A week later Besler writes again, explaining that they have been delayed by lack of carriages, but mentioning one which they propose to hire on the following day. Bruno was anxious to take counsel with Wolfgang Zeileisen.
Several works that survive in Besler's hand are believed to have been dictated by Bruno at this period, and are perhaps those to which Besler refers in the letters. The titles are: On Magic; Theses on Magic; On the Origin, Elements and Causes of Things; a longer but incomplete version of the Lullian Medicine; and On Mathematical Magic. 
Next to the Lullian studies that wasted Bruno's time and energy, the reader is most puzzled by his long work On Magic. We have already considered the problem.  It has to be remembered that the theme natural magic, that is to say, the medley of misunderstood and misrepresented devices -- technical and other, which was covered by this title -- took at the time and especially among those without technical knowledge, somewhat the place of what might now be called the "wonders of science." Many phenomena that we now explain on scientific grounds were then treated as "magic that worked according to rule." Of such was believed to be the nature of Bruno's marvellous memory for which exalted persons were always seeking "the rules." In the MS. On Magic, Bruno considers Lullian symbolism as the avenue to wisdom. He reviews the "magical" attempts of various peoples, defines natural magic as "the application of the passive and active properties of things as in medicine and chemistry," and points out that Aristotle used the term magus as a synonym for wise.  He includes in his survey "veneric or malevolent magic," but he is striving towards a synthetic philosophy based on most diverse sources. He enunciates a cosmic hierarchy  and cosmic metabolism;  he reiterates his conviction that every soul and spirit has a certain continuity with the spirit of the universe;  he is again considering the hypothesis of a Void. 
Bruno's unhappily named tract, On Mathematical Magic, is a philosophical work illustrated by mathematical forms. Thus the first sentence states: "God floweth into the angels, the angels into celestial bodies..." while the first section of the second paragraph runs: "Thus God or the emanation from God has descended through the world to the animal; and verily the animal has ascended through the world to God." It is a "scala naturae," partly Aristotelian and partly inspired by Bruno's reflections on Infinity.
On the Origins and Elements of Things, and on Their Causes is dated 16th March, 1590. It opens thus: "The efficient and moving causes of things are intellect and soul, above which is a single absolute origin, mind or truth, of which the essence and power are infinite, intensively and extensively." The Averroist conception of the continuity of the spirit Bruno re-enunciates as a theory of all things "linked in absolute mind or truth ... a single infinite space."  He closes with an elaborate figure of "influences" from the sun, but remarks that none of these influences are conveyed from heaven to individuals below unless by some seed brought to the individual at an appropriate time and place, thus applying and limiting the general and universal quality.
No doubt Bruno profited by his leisure during this year 1589-90 to make substantial progress with the great Latin poems in which his developed philosophy is set forth.
d. Frankfurt, Zurich and Frankfurt Again (1590-91)
There is some obscurity in the movements of Bruno from the time of his departure with Jerome Besler from Helmstedt on 23rd April, 1590. Did they visit Besler's uncle at Magdeburg? In any event, he was soon on his way in the opposite direction travelling to Frankfurt on the Main, where he arrived probably at the beginning of July. At Frankfurt he devoted himself to the production of the great Latin works which had been in his mind and partly on paper from the period of his sojourn in London. As usual, a publisher was at once forthcoming, and indeed the Frankfurt firm of John Wechel and Peter Fischer smoothed his path in every way. The Wechels had been in contact with Sir Philip Sidney (who had died four years previously) and this may have led to Bruno's introduction to them. On 2nd July, 1590, Bruno petitioned the Senate for permission to lodge in Wechel's house, but this was refused.  Not to be beaten, the printer succeeded in obtaining permission for him to dwell in the Carmelite Monastery, and here he was established for six or eight months. Yet he did not see the first of his great poems completely through the press. The volume  appeared with no preface from Bruno, but with a Dedication to the Duke of Brunswick,  penned by the faithful John Wechel. The title is Five Books on the Threefold Minimum and on Mensuration for the Foundation of the Three Speculative Sciences and Many Active Arts. Wechel, expressing Bruno's desire to dedicate the volume in gratitude to Duke Henry Julius, describes how the author actually carved his own figures for printing, and corrected every detail of the book until, when he had reached the very last folio, he was suddenly "torn from us." At his request, the publishers therefore offered the volume to the Duke in his name and their own.  This Dedication is dated "The Ides of February 1591" so that Bruno had probably left Frankfurt about the end of January. The guess has been hazarded that the civic ban on Bruno's residence in Frankfurt was suddenly put into operation. All we know is that he journeyed to Zurich where he was among a congenial circle of friends. 
There survives, perhaps from the sojourn in Frankfurt at this period, or from the visit to Zurich, the first draft of a work expanded later during his last months of freedom at Padua, On Links. 
Among his Zurich friends was a young Swiss, John Henry Heinz, son of a learned and wealthy Swiss Protestant who had married a Bavarian lady and settled in Augsburg. The young John Henry had, however, aroused the wrath of the City Council, apparently because he took the wrong view of the New Calendar. After some adventures he and his brother bought the castle of Elgg in the canton of Zurich where they entertained scholars and pursued their studies, among which were alchemical investigations. Bruno wrote for this friend his work in three books, On the Composition of Images, Signs, and Ideas for all sorts of Discoveries, Dispositions and Recollections, which was published within a few months by Wechel.  The preface gives a glimpse of the answer to a question that must present itself to every student of Bruno. Why should this man, occupied with the formulation of a lofty philosophy, have turned aside and spent so much time on the idle elaborations of logic and mnemonics devised by Raymond Lull?
Idea [he tells us], imagination, analogy, figure, arrangement, notation -- this is the universe of God, the work of nature and of reason, and is possessed also by the analogy thereof, so that nature may admirably reflect divine action, and human talent may thereupon rival the operation of nature and almost reach yet more exalted things. Who doth not see with how few elements nature maketh so many things? No one indeed is ignorant of how she doth variously place, order, compound, move, and apply the same Four [elements] and under various signatures she advances these forms and figures from the depth of potentiality to the sublimity of action. And, by immortal God what can be easier to man than the use of number? ... The whole light thereof is more present, clear and understood by our intelligence than the light of the sun to our eyes ... Why is that which is present to us even over the whole heaven yet believed by us to be remote? Because the eye seeth other things, but it seeth not itself. And what is this eye which thus seeth other things that it may see itself? That which seeth all things in itself, and which is all things at the same time. To such sublime reason should we be akin if we had power to understand the substance of our nature, so that our eye might perceive itself and our mind might embrace itself. Then would it be possible to understand all things, nor would it even be hard to accomplish all things.
He quotes Aristotle: "Our intelligence, that is the operation of our intellect, is either fantasy or not without fantasy," and again, "We understand naught unless we observe the images."
"This is to say" [explains Bruno]:
we comprehend not by any simplicity, mode or unity but through composition, collation and a plurality of terms, making use of discourse and reflection. And if our talent is thus, thus too should without doubt be the works thereof, that, by enquiry, motion, judgement, arrangement and memory, it may avoid wandering away from the mirror and may thus not be moved without images. And if a polished and smooth mirror be placed here by Nature, and if by art, the light of the reckoning of the Canons doth prosper and glow on the horizon, immediately by reason of the faculty bestowed on us by the clear images of things coming into view, we are directed toward that supreme joy in the composite nature of action which indeed most beseemeth man when most he is man.... In the first Book are generalities which deal with the diverse kinds of meaning; the various conditions are explained in which subjects are visible and are disposed, images are impressed and inscribed. We then teach how to build various sorts of halls and spaces, and when at length they are built we shew in them [lit., and we shew them when built; in them at length are] all things which can be uttered, known or imagined; all arts, languages, works, signs. In the second Book are twelve figures of princes ...
with their symbolic implications; while in the third Book the author reverts to the figures of the Thirty Seals.  Among the devices in this work to assist the memory is some mere doggerel verse.
Another of Bruno's works may be traced to his visit to Zurich. For he met there his pupil Raffaele Eglin (Raffaele Eglinus Iconius).  Eglin gives a vivid description of Bruno "standing on one leg, going as fast as the pen could follow, at once dictating and reflecting; so rapidly did his talent work, so great was the power of his mind." From the notes thus taken, Eglin published a work at Zurich in 1595, when the prison doors had already closed on Bruno. The ponderous title of the volume is Survey of Metaphysical Terms for the Understanding of Logic and the Study of Philosophy excerpted from the manuscript of Jordanus Brunus the Nolan, on the Scale of Being.  The arrangement is suggested by the fifth Book of the Metaphysics of Aristotle, being a series of brief paragraphs discussing each term. Characteristically, Bruno chooses as his first two terms Substance and Truth. Eglin's Dedication is inscribed "To the noble youth Frederick à Sales, son of the most generous John." Eglin addresses Frederick à Sales almost as Bruno might have done, "not because thou art in need of his words, but because alone and best of all thou dost understand and dost love." He refers to their discussion concerning Jordanus at the house of Frederick's father the previous autumn. Eglin's pious care for Bruno's writings was not exhausted by the publication of this small volume, for in 1609 when he had become Professor of Theology at Marburg, he republished the work with a second Part, also from manuscript, entitled Scale of Practice or the Application of Being. 
Probably Bruno spent at least some weeks at Zurich, returning to Frankfurt perhaps in the spring of 1591 to supervise the printing of the volume dedicated to Heinz,  and the production at last of the second and final volume of his great trilogy of Latin philosophical works in verse and prose. We can but marvel as to how he raised means to cover the hundreds of miles involved in each of these journeys. Perhaps to those free of all possessions, travel was almost as cheap as residence in a fixed spot! Bruno himself in his evidence at Venice stated that he had spent six months in Frankfurt. After examining all other hypotheses, our two best authorities, Tocco and Spampanato, both conclude that this must refer only to his second sojourn, which may have extended from March to September 1591. Perhaps his silence concerning the first months in Frankfurt was due to reluctance to account for his sudden departure to Zurich or to mention the Zurich visit.
Bruno's last months in Frankfurt were occupied with the proofs of the second volume of his Latin masterpieces in verse and prose. It contains two works: On the Monad, on Number and Form in One Book, being a Sequel to the Five Books on the Great Minimum and on Measurement; and the finest of all the Latin works, On the Innumerable, the Immense, the Formless; On the Universe and Worlds, in eight Books.  The volume is prefaced by a Dedication, this time from Bruno's own hand, to Duke Henry Julius of Brunswick. It is entitled Dedicatory Letter and Key and deals with the previous poem of the great series as well as with the two works to which it is attached:
In the first volume we studiously desired [sic], in the second we sought in uncertainty, in the third we arrived most clearly. In the first, sense-perception is most important; in the second, words; in the third, the thing itself. The first concerns what is within us; the second, things heard; the third, that which is discovered. In the first, the method is mathematical; in the second, divine [i.e., theological]; but in the third it is natural.
The first deals with simple objects, the second with abstract, the third with composite. In the first, wisdom pervadeth the body; in the second, the shadow; in the third, the soul. The elements of the first are limit, minimum, size; the subjects are the line, the angle, the triangle; learned doctors, the temple of Apollo, of Minerva and of Venus, which are [sic] constructed in circles which are in apposition, interpenetrating and containing one another; in which figures, numbers and measurements are all implicit, sought out, explicit by means of definitions, axioms, theorems. In the second work the monad is the substance of the matter; number is the internal quality or specific difference; form is the external accident and signature. We contemplate the monad in the circle; number in the triplex triad of the other archetypes; and form in the individual we contemplate according to the element thereof, in the totality however according to the effect thereof. Viewed according to the monad all things are in harmony; viewed by number they mostly differ one from another; but viewed according to form they are in complete opposition. For the monad is the individual substance of a thing, number is an unfolding of the substance, but form is indeed the orderly flowing forth from the [original] site of the unfolded origins. The monad is that which is absolutely true; number is goodness in its own nature; form is beauty in a certain relation. For truth is different in different situations; the good is different to different persons and in different places; beauty is different to different persons, in different places and at different times. The monad teacheth him who is happy to remain so; him who is unhappy the monad teaches to change his place; number teacheth to change his name; form his condition.
In the third work, entrance from darkness to light is given by means of colour. The distinction is drawn between the boundary, the finite and the infinite. And again between the efficient cause, the element and the effect. Furthermore, between motion, quiet and immobility. It is shewn that the principal dements in the universe are water, light and air; the principal substances are sun, our earth, and the Heaven (under one Being, lord of all things, unconditioned by any form). So that the hindrance to natural knowledge and the main foundation of ignorance is the failure to perceive in things the harmony between substances, motions and qualities. For the perfection of the universe proceedeth from unity, truth and goodness, by the virtue of active force, by the disposition of passive force and by the worthiness of results. This true perfection can exist only in an innumerable multitude, in immense size and in the evident beauty of order. Thus by a certain circle of learning (encyclopedia), all things are brought forth, directed and applied. They are distinguished in a threefold order in succession on a single ladder, so that ease may exist with brevity, truth with ease, and certitude with truth. Furthermore seemliness is considered in the matter, order in the diversity of the propositions, sufficiency in the paucity of the undetermined (mediorum) whereby nature hath meaning, reason is regarded, God worketh all things in all things. It is these things, many of which when seen from afar may be deemed odious and absurd, but if observed more nearly they will be found beautiful and true, and when known very closely they will be wholly approved, most lovely and certain withal. In their light will undoubtedly be dispersed those gloomy fabrications which by the compulsion of custom are thought to be true and beautiful, though in the even balance of reason they are discovered to be uncertain and infelicitous. At length by the light of that nature which shineth forth by means of our sense-perceptions and demonstrations, they are recognized as most vile and impossible.
The reader will be no less grateful than is the present writer that Bruno has given us his sketch of what he regarded as the most important features of these volumes. We will not attempt to give in a few pages even a sketch of their whole content. A word may be added as to the form of these works. Bruno is perhaps most eloquent in the Lucretian Latin verse which he has chosen as the vehicle of his thought in these volumes. It is true that scholars will at times be startled by his Latinity, and Bruno boldly defends his coinage of new words. But the lines roll forth with sweeping vigour. Certain passages, especially in the De immenso et innumerabilibus carry the reader with irresistible force into the realm of Bruno's thought. But as though he suspected that this would be his last effort to deliver his message, Bruno has appended to each canto or "chapter" a prose exposition or commentary. These are among the most lucid passages of his writings.
The shades were gathering. His nostalgia for Italy was reinforced by his eager acceptance of new adventure, perhaps too by his never-quenched hope for reconciliation with the Church. To Italy he went and we turn to the sombre tragedy of his last years.