information:extraction, structural:scholar_edition, linguistic:voice_change, information:highlighting, stylistic:tone
England, 1583–1585

In April 1583, Bruno went to England with letters of recommendation from Henry III as a guest of the French ambassador, Michel de Castelnau. Bruno lived at the French embassy with the lexicographer John Florio. There he became acquainted with the poet Philip Sidney (to whom he dedicated two books) and other members of the Hermetic circle around John Dee, though there is no evidence that Bruno ever met Dee himself. He also lectured at Oxford, and unsuccessfully sought a teaching position there. His views were controversial, notably with John Underhill, Rector of Lincoln College and subsequently bishop of Oxford, and George Abbot, who later became Archbishop of Canterbury. Abbot mocked 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", and found Bruno had both plagiarized and misrepresented Ficino 's work, leading Bruno to return to the continent.

Nevertheless, his stay in England was fruitful. During that time Bruno completed and published some of his most important works, the six "Italian Dialogues", including the cosmological tracts La cena de le ceneri (The Ash Wednesday Supper, 1584), De la causa, principio et uno (On Cause, Principle and Unity, 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 gli eroici furori (On the Heroic Frenzies, 1585). Some of these were printed by John Charlewood. Some of the works that Bruno published in London, notably The Ash Wednesday Supper, appear to have given offense. Once again, Bruno's controversial views and tactless language lost him the support of his friends. John Bossy has advanced the theory that, while staying in the French Embassy in London, Bruno was also spying on Catholic conspirators, under the pseudonym "Henry Fagot", for Sir Francis Walsingham, Queen Elizabeth 's Secretary of State.

Bruno is sometimes cited as being the first to propose that the universe is infinite, which he did during his time in England, but an English scientist, Thomas Digges, put forth this idea in a published work in 1576, some eight years earlier than Bruno. An infinite universe and the possibility of alien life had also been earlier suggested by German Catholic Cardinal Nicholas of Cusa in "On Learned Ignorance" published in 1440 and Bruno attributed his understanding of multiple worlds to this earlier scholar, who he called "the divine Cusanus".