Ordained as a priest, his philosophy focused on seeking virtue and truth, at the expense of narrow theological disputes. In a time of violent religious sectarianism, Bruno believed in the peaceful co-existence of all religions. He anticipated the modern theory of an infinite universe without center, at a time when most people thought the earth was the center of the Universe and that astronomy was dictated by the Bible. His teachings also contained some seeds of modern physics, postulating a unity of matter and form to replace Aristotle’s duality.

The son of a professional soldier, Bruno was born in Nola, Italy. In 1572, at age twenty-four, he was ordained as a priest, despite his known proclivity for unconventional views. From this point forward he spent most of his life as a wandering scholar and teacher, constantly engaging in philosophical and theological disputes and attacking official views, which forced him to move from city to city to avoid trial and imprisonment.

His movements were affected by unpredictable local shifts in religious tolerance. He lived in Naples, Rome, Geneva, Paris, and London before returning to Italy to seek an academic position which was given to his more famous contemporary, Galileo. He was denounced and tried in Venice, but the case was moved to Rome. His trial was remarkably protracted, lasting seven years. Finally, as a result of his refusal to recant his beliefs and by order of Pope Clement, he was burned at the stake in Rome in 1600.