There were at this time in Paris two great Universities, one the College de France, with liberal tendencies, and opposed to the Jesuits and all pedantry; the other the Sorbonne, for centuries the guardian of the Catholic faith, endowed with the right of censorship, which must have been exercised over Bruno's works. In which of these, though surely in one of them, Bruno was made an Extraordinary Lecturer history has failed to record. He must have offended both, since he was anxious to be taken back into the Church, yet was revolutionary in his teaching. More than thirty years later Nostitz, one of his pupils, paid tribute to his versatility and skill, saying "he was able to discourse impromptu on any suggested subject, to speak extensively and elaborately without preparation, so that he attracted many pupils and admirers in Paris." (McIntyre). But Bruno belonged to the literally peripatetic school, and in 1583 he forsook Paris for London, because as he says of "tumults," leaving it to the imagination whether these were civil or scholastic.
Elizabeth reigned at this time; her influence made England a harbor of safety for religious and other mental suspects. She had a penchant for Italians and their language; two of her physicians were Italians, and Florio was ever welcome at her court. To this court Bruno also was welcomed, and, basking for sometime in the sunshine of her regard and patronage, passed there the happiest portion of his unhappy life. Oxford was at that time the stronghold of Aristotelianism. One of its statutes ordained that "Bachelors and Masters who did not follow Aristotle faithfully were liable to a fine of five shillings for every point of divergence, and for every fault committed against the Logic of the Organon." (McIntyre). In Oxford at this time, unfortunately, theology was the only live issue; of science as of real scholarship there was little or none. (Its predominant trait of those days is still, perhaps, its dominant feature to-day). To this university Bruno addressed a letter, couched in vainglorious and egotistical terms, craving permission to lecture there. This was not received with favor, while his doctrines met with small encouragement at this ancient seat of learning, which Bruno later stigmatized as the "widow of true science." But opportunity was afforded him to dispute publicly before a noble visitor in June, 1583, a Polish prince; one Alasco, for whom great public entertainment had been provided. His opponent, defeated by fifteen unanswerable syllogisms, resorted to scurrility and abuse. This public exhibition put an end to the lectures on the Immortality of the Soul which Bruno had been allowed to give, and he returned to London.
Shortly after this he published his Cena (Ash Wednesday Supper) in which he ridiculed the Oxford doctors, saying among other things that they were much better acquainted with beer than with Greek. But he criticised too cynically and lost thereby in popularity. This led to the appearance of the Causa, a dialogue, in which he was less vindictive. He admitted in this that there was much in the old institution which was admirable; that it was even the first in Europe, that speculative philosophy first flourished there, and that thence, "the splendor of one of the noblest and rarest spheres of philosophy, in our times almost extinct, was diffused to all other academies in civilized lands." What he most condemned was the too great attention given to language and words while the realistics for which words stand were neglected. Doctors were easily made and doctorates too cheaply bought. His charge in brief was that they mistook the shadow for the substance; a charge even yet too commonly justified among the strongholds of theology and other speculative dogmas.
Returning to London after this experience Bruno went to live with Mauvissiere, the French Ambassador. While the English records make no mention of his presence it is yet quite certain that he was frequently at Court, and that men like Sydney, Greville, Temple and others were his frequent associates. But as the Ambassador's influence was on the wane, he was not equal to his great trust. At this time our philosopher spoke of himself as one "whom the foolish hate, the ignoble despise, whom the wise love, the learned admire," etc. (McIntyre). Of Queen Elizabeth he wrote in most fulsome phrases, such as she too dearly loved. Before his judges, a few years later, Bruno apologized for his exaggerated expressions concerning a Protestant ruler, claiming that when he spoke of her as "divine" he meant it not as a term of worship, but as an epithet like those which the ancients bestowed upon their rulers; claiming further that he knew he erred in thus praising a heretic.
Bruno published seven works in England. The first was "Explicatio triginta Sigillorum," the Thirty Seals thus explained being hints for acquiring, arranging and remembering all arts and sciences. To it was added his Sigillus Sigillorum for comparing and explaining all mental operations. Then came an Italian dialogue "La Cena de le Ceneri" or Ash Wednesday Supper. This was written in praise and extension of the Copernican theory, indeed quite exceeding it in teaching the identity of matter, the infinity of the universe, the possibility of life on other spheres, with a painstaking attempt to show that these notions do not conflict with those of Mother Church. Next came "De Causa, Principio et Uno." (Cause, Principle and Unity). This treated of the immanence of spirit, the eternity of matter, the potential divinity of life, the origin of sin and death, and many other similar abstruse topics. It was followed by De l'Infinito Universo ed Mondi, with numerous reasons for believing the universe to be infinite and full of innumerable worlds, with the divine essence everywhere pervading.
All these works appeared in 1583. In 1584 appeared his "Spacio de la Bestia Triofante" or Expulsion of the Triumphant Beast. In this prose poem Jupiter, repenting his errors, resolves to expel the many beasts that occupy his heavenly sphere—the constellations—and to substitute for them the virtues. In the council of the gods convened by him many subjects are discussed, among them the history of religions, the contrasts between natural and revealed religions and the fundamental forms of morality. In this allegory Jupiter represents of course the human spirit; the Bear, the Scorpion, etc., are the vices to be expelled. Unfortunately the book was quite generally regarded as attack upon the Church or the Pope, though what he really struck at was the credulity of mankind. It was dedicated to Sir Philip Sydney. Then came his "Cabala del Cavallo Pegasio" or Cabal, dedicated to a suppositious Bishop who was made to impersonate the spirit of ignorance and sloth. It is a mordant satire on Asinity, including credulity and unquestioning faith. After this he dedicated another work to Sidney. "Degl' Heroici Furori" (Enthusiasms of the Noble), a collection of sonnets with prose commentaries, like Dante's Vita Nuova, touching on the love for spiritual beauty arising from that for physical beauty attaining a climax in a sort of ecstasy by union with the divine. These sonnets possess a very high literary value aside from their other interest.
When his ambassadorial patron was recalled Bruno probably returned to Paris with him, during the latter part of 1585. Here he spent a year amidst constant turmoil and excitement, and at his own expense. Though he attempted reconciliation with the Church he was regarded as an apostate. He held one more public disputation in which he advanced one hundred and twenty theses against the teaching of the Sorbonne, his side being taken by its rival, the College de France. The outcome cannot have been brilliantly favorable, since he soon after left Paris, in June, 1586. The collection of charges above alluded to was published in Paris after Bruno's departure, and again in Wittenberg, under the title "Excubitor" (The Ambassador). It was an arraignment of the Aristotelians, based on the words of that great master himself. Bruno claimed the same right to criticise Aristotle that the latter claimed to criticise his predecessors. In it Bruno says, "It is a poor mind that will think with the multitude because it is a multitude; truth is not altered by the opinions of the vulgar or the confirmation of the many;"—and again—"it is more blessed to be wise in truth in face of opinion than to be wise in opinion in face of truth." (McIntyre, p. 50).
In addition to this Bruno had also published, before leaving Paris, a commentary on the Physics of Aristotle.
Tarrying somewhat by the wayside Bruno reached Wittenberg, where, in 1586, he matriculated at its University, Marburg having curtly rejected him. Describing him here McIntyre styles him the "Knight Errant of Philosophy." Here Lutheranism dominated the theological faculty, while the philosophical faculty was dominated by Calvinism; views concerning the person of Christ, the "Real Presence," and the doctrine of Predestination keeping them apart in spite of Melancthon's attempt to reunite the two factions. From the Lutheran party Bruno obtained permission to lecture, and so for two years he taught from the Organon of Aristotle, as well as the writings of Raymond Lulli. To the University senate he dedicated a work on Lulli, "De Lampade Combinatoria Lulliana," whose chief purpose was to teach one how to find "an indefinite number of propositions and middle terms for speaking and arguing." He regarded it as the only key to the Lullian writings, as well as a clue to a great many of the mysteries of the Pythagoreans and Cabalists. It was soon followed by "De Progressu et Lampade Venatoria Logicorum," intended to enable one to "dispute promptly and copiously on any subject."
But again fate compelled a change of residence, for the Calvanistic and Ducal party gained in political ascendancy, to which party Bruno, as a Copernican, would have appeared as a heretic. After delivering an eloquent address of farewell he moved on, his next abiding place being Prague, where Rudolph II, of Bohemia, was posing as the friend of all learned men. Here he already had friends at court, and here he introduced himself with another Lullian work. To the Emperor he next dedicated a work of iconoclastic type, "One hundred and sixty articles against the mathematicians and philosophers of the day." For this the Emperor granted him the sum of three hundred dollars, and in January, 1589, he shifted again to Helmstadt, in Brunswick, where he matriculated again in the then youngest of the German Universities. This had been founded only twelve years before by Duke Julius, who was extremely liberal in his views, and intended to found a model institution, in which theology should not play too dominant a part. But while he received here a certain recognition fate again sported with him, for the Duke died four months after his arrival. Bruno obtained permission to pronounce a funeral oration, desiring to express his gratitude to the memory of one who had opened such an institution, so free to all lovers of the Muses and to exiles like himself, who were here protected from the greedy maw of the Roman wolf, whereas in Italy he had been chained to a superstitious cult. It was full of allusions to the papal tyranny which was infecting the world with the rankest poison of ignorance and vice.