Born Filippo Bruno in Nola, Italy, Bruno took the name Giordano (for the Jordan River) when he entered the Dominican monastery in Naples. Bruno was a good student, but an independent thinker in an order that demanded intellectual discipline. His work in mnemonics brought him attention, but he was suspected of heretical views on the Trinity, and saint's images, and there was a threat of formal charges. In 1576, not long after having been ordained as a Dominican priest, Bruno left the order and began to move restlessly about Europe (Toulouse, Paris, London, Wittenberg, Prague, Frankfurt) writing and teaching. While in London he published two of his best known philosophical/cosmological works, La cena de le cenari (Ash Wednesday Supper) and De Vinfinito universo et mondi (On the Infinite Universe and Worlds) in 1584. These volumes contain his most extensive writings on the subject of astronomy and the Copernican theory. (There is no evidence that he met Thomas Digges during his time in London, but they had definite mutual acquaintances.) His books and sojourns to Protestant countries only exacerbated his Italian problems, and upon unwisely returning to that country in 1592 he was soon arrested, imprisoned, and finally tried before the Inquisition as a heretic. Refusing to recant, he was burned at the stake in 1600.

Bruno's iconoclastic philosophy rejected the notion of man at the center of the universe, believed in the immanence of the divine being in all things, and that reality was purely constituted by the human mind, which itself partook of the nature of the divine being.