Giordano Bruno

Bruno was denounced to the Venetian Inquisition by his own patron Giovanni Mocenigo in May 1592, transferred to Rome, held for seven years, refused to recant in December 1599, and was burned at the Campo de' Fiori on 17 February 1600.

The nineteenth century made him the martyr of science, executed for teaching that the earth moves. That is not sustainable. Copernicus's De revolutionibus was not placed on the Index until 1616, sixteen years after Bruno died; heliocentrism was not a heresy in 1600 and he cannot have been condemned for holding it.

The charge list, reconstructed by Luigi Firpo from the Sommario of the trial that Angelo Mercati found in the Vatican archives in 1940, is theological almost throughout: denial of the Trinity, of the divinity of Christ, of the Incarnation, of the virginity of Mary and of transubstantiation, together with metempsychosis, the practice of magic and divination, and the plurality and eternity of worlds. The document containing the eight propositions finally put to him is lost, so the exact final formulation cannot be checked.

The defensible statement is therefore narrower than either legend. He was condemned as a theological heretic, and he was one, he denied central Christian doctrines and said so repeatedly. His cosmology entered the case, but as metaphysics and theology rather than as astronomy: an infinity of worlds and an eternal universe bear on creation, providence and the uniqueness of the Incarnation, which is why they are on the list. Not a martyr for Copernicanism; not unconnected to his cosmology either.

In 1964 Frances Yates published Giordano Bruno and the Hermetic Tradition and reframed the field. Her Bruno was not a proto-scientist at all but a Hermetic magus, a religious reformer who wanted to restore the Egyptian religion described in the Hermetic writings, and who embraced the Copernican system not as astronomy but as a hieroglyph, a sign in the heavens of the magical truth he was preaching. She was, note, arguing against the martyr-of-science legend, not for it.

The book's influence was enormous and its central thesis has not held. Robert Westman and J. E. McGuire attacked it directly in 1977; Brian Vickers's 1984 collection declared itself entirely unconvinced; Hilary Gatti argued in 1999 for a Bruno seriously engaged with the science of his day; Ingrid Rowland's 2008 biography works from the trial documents. The most telling single indicator is that the current Stanford Encyclopedia of Philosophy entry on Bruno does not mention Yates at all.

It is worth being clear about what has been rejected, because Yates is still cited constantly in esoteric writing as though her account were settled history. What survives is her demonstration that Renaissance Hermeticism was a large, serious intellectual current that historians had been ignoring, and that magic and natural philosophy were not separate worlds. What has not survived is the strong claim, that Bruno's Copernicanism was essentially magical, and that Hermeticism was the engine of the scientific revolution. Anyone reading her should have both halves of that in view.