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Giordano Bruno (1548 Nola – Rome, February 17, 1600) was an Italian philosopher, priest, cosmologist, and occultist. Bruno is known for his system of mnemonics based upon organized knowledge and as an early proponent of the idea of an infinite and homogeneous universe. Burned at the stake as a heretic by the Roman Inquisition, Bruno is often seen as the first martyr to the cause of free-thought. [1]



Early life

Born in Nola (in Campania, then part of the Kingdom of Naples) in 1548, he was originally named Filippo Bruno. His father was Giovanni Bruno, a soldier. At the age of eleven he traveled to Naples to study the Trivium. At 15, Bruno entered the Dominican Order, taking the name of Giordano from Giordano Crispo, his metaphysics tutor. He continued his studies, completing his novitiate, and becoming an ordained priest in 1572.

He was interested in philosophy, and was an expert on the art of memory; he wrote books on mnemonic technique, which Frances Yates contends may have been disguised Hermetic tracts. The writings attributed to Hermes Trismegistus had played an important role in the Renaissance Neoplatonic revival. At that time they were thought to date uniformly to the earliest days of ancient Egypt and to encode a form of "pristine wisdom" ("prisca philosophia").


They are now believed to date mostly from about 300 A.D. and are associated with Neoplatonism.



Woodcut illustration of one of Giordano Bruno's mnemonic devices:

in the spandrels are the four classical elements: earth, air fire, water



While the Hermetic Tradition was a major influence on Bruno, he also absorbed and developed the heliocentric ideas of Copernicus.


Other significant influences included Thomas Aquinas, whose works he had to study in depth as a novice and for whom he always expressed a curiously deep admiration ([2]), Averroes, whose idea of a universal mind resonates through Bruno's work, Duns Scotus, the Renaissance Neoplatonist Marsilio Ficino, and, last but certainly not least, Nicholas of Cusa's ideas on infinity and indeterminacy, particularly the idea of an infinite universe where Earth has no special place.


Bruno developed a pantheistic hylozoistic system, essentially incompatible with orthodox Christian Trinitarian beliefs.

In 1576 he left Naples to avoid the attention of the Inquisition. He left Rome for the same reason and abandoned the Dominican order. He travelled to Geneva and briefly joined the Calvinists, before he was excommunicated, ostensibly for slandering the philosophy professor Antoine de la Faye. After Bruno apologized his excommunication was revoked, but in autumn 1579, deeply disappointed by Calvinist intolerance, he left for France.

He went first to Lyon, but he could not find work there and in late 1579 he arrived in Toulouse, at that time a Catholic stronghold, where he obtained a position as lecturer of philosophy. After the bitter experience in Geneva, he also tried to revert to mainstream Catholicism, but he was denied absolution by the Jesuit priest that he approached.


After religious strife broke out in Toulouse in summer 1581, he moved to Paris, where first he held a cycle of thirty lectures on theological topics. At this time, he also began to gain fame for his prodigious memory. Bruno's feats of memory were based, at least in part, on his elaborate system of mnemonics, but some of his contemporaries found it easier to attribute them to magical powers. His talents attracted the benevolent attention of the king Henry III, who supported a conciliatory, middle-of-the-road cultural policy between Catholic and Protestant extremism.

In Paris he enjoyed the protection of his powerful French patrons. During this period, he published several works on mnemonics, a.o. "De umbris idearum" (The Shadows of Ideas, 1582), "Ars Memoriae" (The Art of Memory, 1582), "Cantus Circaeus" (Circe's Song, 1582), based on his model of organised knowledge, opposed to that of Petrus Ramus. In 1582 Bruno also published a comedy summarizing some of his philosophical positions, titled "Il Candelaio" ("The Torchbearer").



Travel years

In April 1583, he went to England with letters of recommendation from Henry III, working for the French ambassador, Michel de Castelnau.


There he became acquainted with the poet Philip Sidney and with the Hermetic circle around John Dee. He also unsuccessfully sought a teaching position at Oxford, where however he held lectures. His views spurred controversy, notably with John Underhill, Rector of Lincoln College and from 1589 bishop of Oxford, and George Abbot, who later became Archbishop of Canterbury, who poked fun at Bruno for supporting “the opinion of Copernicus that the earth did go round, and the heavens did stand still; whereas in truth it was his own head which rather did run round, and his brains did not stand still.”([3]) and who reports accusations of plagiarising Ficino's work. Still, the English period was a fruitful one.


During that time Bruno completed and published some of his most important works, the "Italian Dialogues", including the cosmological tracts "La Cena de le Ceneri" (The Ash Wednesday Supper, 1584), "De la Causa, Principio et Uno" (On Cause, Prime Origin and the One, 1584), "De l'Infinito Universo et Mondi" (On the Infinite Universe and Worlds, 1584) as well as "Lo Spaccio de la Bestia Trionfante" (The Expulsion of the Triumphant Beast, 1584) and "De gl' Heroici Furori" (On Heroic Frenzies, 1585).


Some of the works that Bruno published in London, notably the "The Ash Wednesday Supper", appear to have given offense. It was not the first time, nor was it to be the last, that Bruno's controversial views coupled with his abrasive sarcasm lost him the support of his friends.

In October 1585, after the French embassy in London was attacked by a mob, he returned to Paris with Castelnau, finding a tense political situation. Moreover, his 120 theses against Aristotelian natural science and his pamphlets against the Roman Catholic mathematician Fabrizio Mordente soon put him in ill favor. In 1586, following a violent quarrel about Mordente's invention, "the differential compass", he left France for Germany.



Woodcut from Articuli centum et sexaginta adversus huius tempestatis mathematicos atque philosophos,

Prague 1588



In Germany he failed to obtain a teaching position at Marburg, but was granted permission to teach at Wittenberg, where he lectured on Aristotle for two years. However, with a change of intellectual climate there, he was no longer welcome, and went in 1588 to Prague, where he obtained 300 taler from Rudolf II, but no teaching position. He went on to serve briefly as a professor in Helmstedt, but had to flee again when he was excommunicated by the Lutherans, continuing the pattern of Bruno's gaining favor from lay authorities before falling foul of the ecclesiastics of whatever hue.

1591 found him in Frankfurt. Apparently, during the Frankfurt Book Fair, he received an invitation to Venice from the patrician Giovanni Mocenigo, who wished to be instructed in the art of memory, and also heard of a vacant chair in mathematics at the University of Padua. Apparently believing that the Inquisition might have lost some of its impetus, he returned to Italy.

He went first to Padua, where he taught briefly, and applied unsuccessfully for the chair of mathematics, that was assigned instead to Galileo Galilei one year later. Bruno accepted Mocenigo's invitation and moved to Venice in March 1592. For about two months he functioned as an in-house tutor to Mocenigo. When Bruno announced his plan to leave Venice to his host, the latter, who was unhappy with the teachings he had received and had apparently developed a personal rancour towards Bruno, denounced him to the Venetian Inquisition, that had Bruno arrested on May 22, 1592.


Among the numerous charges of blasphemy and heresy brought against him in Venice, based on Mocenigo's denunciation, was his belief in the plurality of worlds, as well as accusations of personal misconduct. Bruno defended himself skillfully, stressing the philosophical character of some of his positions, denying others and admitting that he had had doubts on some matters of dogma.


The Roman Inquisition, however, asked for his transferal to Rome. After several months and some quibbling the Venetian authorities reluctantly consented and Bruno was sent to Rome in February 1593.



The monument to Bruno in the place he was executed,

Campo de' Fiori in Rome.



Close-up of the statue




Trial and death

In Rome he was imprisoned for seven years during his lengthy trial, lastly in the Tower of Nona.


Some important documents about the trial are lost, but others have been preserved, among them a summary of the proceedings that was rediscovered in 1940. [2] The numerous charges against Bruno, based on some of his books as well as on witness accounts, included blasphemy, immoral conduct, and heresy in matters of dogmatic theology, and involved some of the basic doctrines of his philosophy and cosmology.


Luigi Firpo lists them as follows: [3]

  • Holding opinions contrary to the Catholic Faith and speaking against it and its ministers.

  • Holding erroneous opinions about the Trinity, about Christ's divinity and Incarnation.

  • Holding erroneous opinions about Christ.

  • Holding erroneous opinions about Transubstantiation and Mass.

  • Claiming the existence of a plurality of worlds and their eternity.

  • Believing in metempsychosis and in the transmigration of the human soul into brutes.

  • Dealing in magics and divination.

  • Denying the Virginity of Mary.

Bruno continued his Venetian defensive strategy, which consisted in bowing to the Church's dogmatic teachings, while trying to preserve the basis of his philosophy. In particular Bruno held firm to his belief in the plurality of worlds, although he was admonished to abandon it. His trial was overseen by the inquisitor, Cardinal Robert Bellarmine, who demanded a full recantation, which Bruno eventually refused. Instead he appealed in vain to Pope Clement VIII, hoping to save his life through a partial recantation.


The Pope expressed himself in favor of a guilty verdict. Consequently, Bruno was declared a heretic, handed over to secular authorities on February 8, 1600. At his trial he listened to the verdict on his knees, then stood up and said:

"Perhaps you, my judges, pronounce this sentence against me with greater fear than I receive it."

A month or so later he was brought to the Campo de' Fiori, a central Roman market square, his tongue in a gag, tied to a pole naked and burned at the stake, on February 17, 1600.



The conflicts over his execution

All his works were placed on the Index Librorum Prohibitorum in 1603. Four hundred years after his execution, official expression of "profound sorrow" and acknowledgement of error at Bruno's condemnation to death was made, during the papacy of John Paul II. Attempts were made by a group of professors in the Catholic Theological Faculty at Naples, led by the Nolan Domenico Sorrentino, to obtain a full rehabilitation from the Catholic authorities.

In 1885 an international committee for a monument to Bruno on the site of his execution was formed [4], including Victor Hugo, Herbert Spencer, Ernest Renan, Ernst Haeckel, Henrik Ibsen and Ferdinand Gregorovius. [5] [6] The monument was sharply opposed by the clerical party, but was finally erected by the Rome Municipality and inaugurated in 1889.

Some authors have characterized Bruno as a "martyr of science", making a parallel to the Galileo affair. They assert that, even though Bruno's theological beliefs were an important factor in his heresy trial, his Copernicanism and cosmological beliefs also played a significant role for the outcome. Others oppose such a fatal role of the Copernican system for Bruno, and claim the connection to be exaggerated, or outright false. [7] [8]

The Vatican webpage about Bruno's trial provides a different perspective:

"In the same rooms where Giordano Bruno was questioned, for the same important reasons of the relationship between science and faith, at the dawning of the new astronomy and at the decline of Aristotle’s philosophy, sixteen years later, Cardinal Bellarmino, who then contested Bruno’s heretical theses, summoned Galileo Galilei, who also faced a famous inquisitorial trial, which, luckily for him, ended with a simple abjuration." [9]



The cosmology of Bruno's time

According to Aristotle and Plato, the universe was a finite sphere. Its ultimate limit was the primum mobile, whose diurnal rotation was conferred upon it by a transcendental God, not part of the universe, a motionless prime mover and first cause.


The fixed stars were part of this celestial sphere, all at the same fixed distance from the immobile earth at the center of the sphere. Ptolemy had numbered these at 1,022, grouped into 48 constellations. The planets were each fixed to a transparent sphere.

In the first half of the 15th century Nicolaus Cusanus reissued the ideas formulated in Antiquity by Democritus and Lucretius and dropped the Aristotelean cosmos. He envisioned an infinite universe, whose center was everywhere and circumference nowhere, with countless rotating stars the Earth being one of them, of equal importance. He also considered neither the rotation orbits were circular, nor the movement was uniform.

In the second half of the 16th century, the theories of Copernicus began diffusing through Europe. Copernicus conserved the idea of planets fixed to solid spheres, but considered the apparent motion of the stars to be an illusion caused by the rotation of the Earth on its axis; he also preserved the notion of an immobile center, but it was the Sun rather than the Earth. Copernicus also argued the Earth was a planet orbiting the Sun once every year. However he maintained the Ptolemaic hypothesis that the orbits of the planets were composed of perfect circles - deferents and epicycles - and that the stars were fixed on a stationary outer sphere.

Few astronomers of Bruno's time accepted Copernicus's heliocentric model. Among those who did were the Germans Michael Maestlin (1550-1631), Cristoph Rothmann, Johannes Kepler (1571-1630), the Englishman Thomas Digges, author of A Perfit Description of the Caelestial Orbes, and the Italian Galileo Galilei (1564-1642).

Bruno's cosmology was strongly influenced by Cusanus and Copernicus.



Bruno's cosmology

Bruno believed, as is now universally accepted, that the Earth revolves and that the apparent diurnal rotation of the heavens is an illusion caused by the rotation of the Earth around its axis. He also saw no reason to believe that the stellar region was finite, or that all stars were equidistant from a single center of the universe.

In 1584, Bruno published two important philosophical dialogues, in which he argued against the planetary spheres. (Two years later, Rothmann did the same in 1586, as did Tycho Brahe in 1587.) Bruno's infinite universe was filled with a substance -- a "pure air", aether, or spiritus -- that offered no resistance to the heavenly bodies which, in Bruno's view, rather than being fixed, moved under their own impetus.


Most dramatically, he completely abandoned the idea of a hierarchical universe. The Earth was just one more heavenly body, as was the Sun. God had no particular relation to one part of the infinite universe more than any other. God, according to Bruno, was as present on Earth as in the Heavens, an immanent God, the One subsuming in itself the multiplicity of existence, rather than a remote heavenly deity.

Bruno also affirmed that the universe was homogeneous, made up everywhere of the four elements (water, earth, fire, and air), rather than having the stars be composed of a separate quintessence. Essentially, the same physical laws would operate everywhere, although the use of that term is anachronistic. Space and time were both conceived as infinite. There was no room in his stable and permanent universe for the Christian notions of divine Creation and Last Judgement.

Under this model, the Sun was simply one more star, and the stars all suns, each with its own planets. Bruno saw a solar system of a sun/star with planets as the fundamental unit of the universe. According to Bruno, infinite God necessarily created an infinite universe, formed of an infinite number of solar systems, separated by vast regions full of Aether, because empty space could not exist. (Bruno did not arrive at the concept of a galaxy.) Comets were part of a synodus ex mundis of stars, and not -- as other authors sustained at the time -- ephemeral creations, divine instruments, or heavenly messengers. Each comet was a world, a permanent celestial body, formed of the four elements.

Bruno's cosmology is marked by infinitude, homogeneity, and isotropy, with planetary systems distributed evenly throughout. Matter follows an active animistic principle: it is intelligent and discontinuous in structure, made up of discrete atoms. This animism (and a corresponding disdain for mathematics as a means to understanding) is the most dramatic respect in which Bruno's cosmology differs from what today passes for a common-sense picture of the universe.

During the later 16th century, and throughout the 17th century, Bruno's ideas were held up for ridicule, debate, or inspiration. Margaret Cavendish, for example, wrote an entire series of poems against "atoms" and "infinite worlds" in Poems and Fancies in 1664. His true, if partial, rehabilitation would have to wait for the implications of Newtonian cosmology.

Bruno's overall contribution to the birth of modern science is still controversial. Some scholars follow Frances Yates stressing the importance of Bruno's ideas about the universe being infinite and lacking structure as a crucial crosspoint between the old and the new. Others disagree. Others yet see in Bruno's idea of multiple worlds instantiating the infinite possibilities of a pristine, indivisible One a forerunner of Everett's Many-worlds interpretation of quantum mechanics.[10]




"Firstly, I say that the theories on the movement of the earth and on the immobility of the firmament or sky are by me produced on a reasoned and sure basis, which doesn’t undermine the authority of the Holy Scriptures […]. With regard to the sun, I say that it doesn’t rise or set, nor do we see it rise or set, because, if the earth rotates on his axis, what do we mean by rising and setting ..."

- Giordano Bruno,

from the Vatican summary of Bruno's trial ([5]).

"I fought, and that's a lot. I thought I could win ... but nature and luck curbed my endeavour. But it's already something that I took up the struggle, because I see that victory is in the hands of Fate. In me was what was possible and what no future century will be able to deny to me: what a winner could give from his own; that I did not fear death, that I did not submit, my face firm, to anyone of my breed; that I preferred courageous death to pavid life."

- Giordano Bruno,

De Monade

"I cleave the heavens, and soar to the infinite. What others see from afar, I leave far behind me."

- Giordano Bruno



  • The Pope & the Heretic, Michael White

  • Vatican Secret Archives: Summary of the trial against Giordano Bruno, Rome, 1597

  • Luigi Firpo, Il processo di Giordano Bruno, 1993

  • Site of Bruno's execution: 41°53′44″N, 12°28′20″E.

  • Alan Powers, Bristol Community College, Campania Felix: Giordano Bruno’s Candelaio and Naples accessed 27 May 2007

  • Hans-Volkmar Findeisen: „Gegenpapst und Designer des Darwinismus“ – Wer kennt heute eigentlich noch Ernst Haeckel? (in German) accessed 27 May 2007

  • Sheila Rabin at the Stanford Encyclopedia of Philosophy: "Thus, in 1600 there was no official Catholic position on the Copernican system, and it was certainly not a heresy. When Giordano Bruno (1548-1600) was burned at the stake as a heretic, it had nothing to do with his writings in support of Copernican cosmology." Nicolaus Copernicus in the Stanford Encyclopedia of Philosophy (online, accessed 19 November 2005).

  • Similarly, the Catholic Encyclopedia (1908) asserts, "Bruno was not condemned for his defense of the Copernican system of astronomy, nor for his doctrine of the plurality of inhabited worlds, but for his theological errors, among which were the following: that Christ was not God but merely an unusually skilful magician, that the Holy Ghost is the soul of the world, that the Devil will be saved, etc." Turner, William. "Giordano Bruno.” 1908. Catholic Encyclopedia accessed 2 Jan. 2007.

  • Vatican Secret Archives accessed 3 November 2006.

  • [1] Max Tegmark, Parallel Universes, 2003





  • Bruno, GiordanoThe Acentric Labyrinth. Giordano Bruno's Prelude to Contemporary Cosmology, Ramon G. Mendoza PhD, 1995, ISBN 1-85230-640-8

  • Cause, Principle and Unity : And Essays on Magic by Giordano Bruno, ISBN 0-521-59658-0

  • The Cabala of Pegasus by Giordano Bruno, ISBN 0-300-09217-2

  • "Writings of Giordano Bruno"

  • The Pope & the Heretic, Michael White, 2002, ISBN 0-06-018626-7.

  • Giordano Bruno, J. Lewis McIntyre.

  • Giordano Bruno and Renaissance Science, Hilary Gatti, 2002, ISBN 0-8014-8785-4

  • Giordano Bruno: His Life and Thought, With Annotated Translation of His Work -On the Infinite Universe and Worlds,Dorethea Singer,1950.

  • Giordano Bruno: The Forgotten Philosopher, John Kessler.

  • Giordano Bruno, Paul Oskar Kristeller, Collier's Encyclopedia, Vol 4, 1987 ed., pg. 634

  • Giordano Bruno and the Hermetic Tradition, Frances Yates, ISBN 0-226-95007-7

  • Eros and Magic in the Renaissance, Ioan P. Couliano, ISBN 0-226-12315-4.

  • Il processo di Giordano Bruno, Luigi Firpo, 1993

  • Giordano Bruno,Il primo libro della Clavis Magna, ovvero, Il trattato sull'intelligenza artificiale, a cura di Claudio D'Antonio, Di Renzo Editore.

  • Giordano Bruno,Il secondo libro della Clavis Magna, ovvero, Il Sigillo dei Sigilli, a cura di Claudio D'Antonio, Di Renzo Editore.

  • Giordano Bruno, Il terzo libro della Clavis Magna, ovvero, La logica per immagini, a cura di Claudio D'Antonio, Di Renzo Editore

  • Giordano Bruno, Il quarto libro della Clavis Magna, ovvero, L'arte di inventare con Trenta Statue, a cura di Claudio D'Antonio, Di Renzo Editore

  • Giordano Bruno L'incantesimo di Circe, a cura di Claudio D'Antonio, Di Renzo Editore

  • Giordano Bruno, De Umbris Idearum, a cura di Claudio D'Antonio, Di Renzo Editore

  • Guido Del Giudice, La coincidenza degli opposti, Di Renzo Editore, ISBN 8883231104 , 2005

  • Giordano Bruno, Due Orazioni: Oratio Valedictoria - Oratio Consolatoria, a cura di Guido del Giudice, Di Renzo Editore, 2007




  • The 20-km diameter crater Giordano Bruno, named in Bruno's honor, is located on the moon at 103°east lunar longitude, 36° north lunar latitude. It is believed to have been created by a meteorite impact in 1178, witnessed by five English monks as related in Carl Sagan's Cosmos.


  • In 1926 the Theosophical Broadcasting Station Pty Ltd, owned by interests associated with the local branch of Theosophical Society Adyar, was granted a radio broadcasting license in Sydney, Australia. The station's call sign, "2GB" was chosen to honour the Italian philosopher who was much admired by Theosophists. Although the ownership of the station subsequently passed to strictly commercial interests the call sign is retained.