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The Folly of Giordano Bruno
by Prof. Richard W. Pogge, Ohio State University

The folly of mistaking a paradox for a discovery, a metaphor for a proof, a torrent of verbiage for a spring of capital truths, and oneself for an oracle, is inborn in us.

Paul Valery, 1895

Fillipo Bruno (1548-1600) was born in Nola near Naples. Taking the name Giordano upon becoming a member of the Dominican order, he was educated in the Aristotelian and Thomist traditions and eventually came to espouse a mystical Neoplatonism mixed with ideas imbibed from a resurgent interest of that time in the works of the apocryphal Hermes Trismegistus. His heterodox beliefs soon attracted the attention of the Inquisition, first in Naples and then in Rome. To avoid prosecution, he renounced his Dominican vows and fled from Italy in 1576. Between 1576 and 1591, he traveled widely about Europe, writing and teaching under the sponsorship of various patrons. In 1591, he was invited to Venice to be tutor to a prospective patron who shortly thereafter denounced him to the Inquisition. He was sent to Rome in 1592 where he was put on trial and then imprisoned and interrogated intermittently for eight years. Unrepentant, he was convicted of heresy by the Inquisition and executed by burning at the stake in the Piazza Campo di Fiore in Rome in 1600. Among his writings, which cover a wide range of topics of only academic interest to us today (chiefly, Neoplatonism, Hermetical philosophy, and pantheism in a decidedly mystical blend), was an espousal of Copernicanism and an assertion that the stars were an infinity of suns like our own, each circled by worlds inhabited by intelligent beings like ourselves.

In popular accounts of the life of Bruno, it is often said that he was condemned for his Copernicanism and his belief in life on other worlds. He is portrayed as a martyr to free thought, and an early, prosecuted proponent of the modern view of the universe, hounded across Europe by the Inquisition for his beliefs and finally paying the ultimate price for them in a fiery public death. He has become a symbol of the intolerance of authority in the face of new ideas. These accounts, however, often leave out two fundamental aspects of the case of Giordano Bruno that cast matters in a somewhat different light. The first calls into doubt how closely we should link Bruno with the history of astronomy and what came to be called the "Scientific Revolution", and the second offers a perspective on the undeniable tragedy of his life that make him less of a symbol, but in the balance makes him more human.

The one key fact of the study of Bruno's life is that we do not actually know the exact grounds of his conviction on charges of heresy. The simple reason is that the relevant records have been lost. This is quite unlike the state of affairs in the later trial of Galileo, where we have extensive documentation including the forgeries that played a role in the case against him. In the case of Bruno, we must seek clues in contemporary accounts and in an examination of his writings.

Except for certain particular passages that excite our interest today, much of his work had little to do with astronomy. Indeed, Bruno was not an astronomer and demonstrated a very poor grasp of the subject in what he did write. The theme of his On the Infinite Universe and Worlds is not Copernicanism but pantheism, a theme also developed in his On Shadows of Ideas. It appears that his personal cosmology informed his espousal of Copernicus, not the other way around. Much of his work was theological in nature, and constituted a passionate frontal assault on the philosophical basis of the Church's spiritual teachings, especially on the nature of human salvation and on the primacy of the soul (or in modern terms, he opposed the Church's emphasis on spiritualism with an unapologetic and all-encompassing materialism). Copernicanism, where it entered at all, was supporting material not the central thesis. This suggests that the Church's complaint with Bruno was theological not astronomical.

Further support for the idea that Copernicanism was likely to have played only a minor role if any in his conviction comes from the contemporary record of the discussion of this idea. What many popular accounts seem to miss is that the Church did not formally condemnation Copernicanism until well after Bruno's death. While Copernicanism was indeed a topic of discussion and controversy in Bruno's time, few astronomers supported it in 1600, and the Church itself was not to express an official opinion on the matter until 1616. By that time, Galileo's telescopic observations (from 1610 on) had completely changed the intellectual landscape, and the Church only then felt compelled to respond to the rapidly growing controversy. The issue was brought to the fore by the publication of a book by Paolo Antonio Foscarini (1565-1616) that defended Copernicanism against charges made by itinerant preaching monks that it was in conflict with Scripture, casting the issue in theological terms that the Church could no longer ignore.

If Copernicanism were really the grounds upon which Bruno was executed as a heretic in 1600, it would have been explicitly proscribed at that time. It is interesting to note further that one of the inquisitors who condemned Bruno was the Jesuit theologian Robert Bellarmine (1542-1621). This is the same Cardinal Bellarmine who as head of the Collegium Romanum in 1616 was charged by Pope Paul V with examining Copernicanism in the Foscarini case, and who in that same year would admonish Galileo in a private audience not hold or defend the idea (the particulars of what was or was not said in that audience would form the basis of Galileo's trial on charges of heresy in 1633). In none of Bellarmine's writings on the subject in 1616 is any mention made of Bruno's earlier case.

Further, Copernicanism was not actually specifically proscribed as heretical in 1616. After Bellarmine's examination, Copernicus' De Revolutionibus and Foscarini's book (among others) were placed on the Index of Forbidden Books, the former to remain on the Index until specific, minor revisions were made (a few words deleted and some passages excised, but on the whole leaving the basic ideas intact). An official response to be sure, but still a long ways from a definitive ban on Copernicanism in general. Indeed, copies of De Revolutionibus were published in Italy after 1616 (with the prescribed revisions, of course), and the situation was sufficiently ambiguous that Galileo felt free to proceed with his work until his trial in 1633. Had Bruno been executed for heresy on the grounds of Copernicanism, there would have been no room for doubt as to where the Church stood on the matter. Final condemnation did not come until 1664 when Pope Alexander VII prefixed a papal bull to the Index specifically condemning the idea of heliocentricism in general by explicitly banning "all books which affirm the motion of the earth''. The final condemnation, but not the final word. The following two years, 1665-66, were the "Plague Years'' in England during which Isaac Newton, on leave from Cambridge, did his seminal work on calculus, optics, mechanics, and gravity.

The second often overlooked fact of Bruno's life concerns his period of exile between 1576 and 1591. Most brief popular accounts state the bare facts of his peregrinations around Europe, but what is left unsaid is that his wanderings appear to have had less to do with his being hounded by the Inquisition as it did with his own rather difficult personality. While Bruno was fairly successful for a time at finding powerful and sympathetic patrons to shelter him, he invariably did something to alienate and outrage them, usually fairly quickly after entering their service. The Inquisition had little to do with it, as once he left Italy, he was effectively out of their reach. This was especially true of his time spent under the protection of the French Ambassador to protestant England (1583-85) during the reign of Queen Elizabeth I, and his wandering around protestant Germany.

An examination of his actions during this period of exile makes clear that almost all of his misfortunes were brought down upon himself without the Inquisition's help. He outraged the faculty at Oxford with his lectures, he became embroiled in violent quarrels over trivial matters, and generally succeeded in alienating those people best able to protect him. His actions during this period reveal the very hallmark of folly, namely repeated failure to act in his own best interests even when reasonable alternatives were available. His final return to Italy (which resulted in his arrest in Venice a year later) can be seen as being motivated in part by the fact that by 1591 he had effectively burned most of his bridges behind him and thus he had little choice. In many ways, Bruno thrust himself into the flames that rose into the winter skies of the Campo di Fiore on the 17th day of February in 1600.

Bruno was brilliant, contentious, and ultimately self-destructive. There is nothing in his writings that contributed to our knowledge of astronomy in any substantial way, indeed his astronomical writings reveal a poor grasp of the subject on several important points. I think we pay attention to him today in large measure because among other things he vocally espoused (but apparently did not really understand) Copernicanism, an idea which was to become the key insight that led to our view of the world. In addition, his On the Infinite Universe and Worlds appeals to many today because of its apparent resonance with the deeply held conviction that life exists elsewhere in the Universe, despite the fact that proponents of extraterrestrial life would find little of interest within its difficult pages. It also does not hurt his mystique that he came to a rather spectacular and violent ending, ostensibly in punishment for these beliefs by the reigning authorities of his day. In the end, Bruno bet on the right horse (if perhaps for questionable reasons), and thus has become a kind of culture hero instead of a footnote in books on Renaissance philosophy.

History is funny that way.


Broderick, James, 1961, Robert Bellarmine, Saint and Scholar (Westminster, MD.: Newman Press)

di Santillana, Giorgio, 1955, The Crime of Galileo (Chicago: Univ. of Chicago Press)

Singer, Dorothea Waley, 1950, Giordano Bruno, his Life and Thought. (New York: Schuman) [contains an annotated translation of On the Infinite Universe and Worlds]

van Helden, Albert, 1995, Giordano Bruno, hypertext biography as part of the Galileo Project.

White, Andrew Dickson, 1896, The Warfare of Science with Theology in Christendom (New York: D. Appleton & Company), 1978 reprint.

Yates, Frances, 1964, Giordano Bruno and the Hermetic Tradition (Chicago: Univ. of Chicago Press)

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