The seventeenth-century philosopher Spinoza was expelled from the Jewish community of Amsterdam at the age of twenty-four due to 'chilling heretical views' and was eventually condemned by all religious authorities because he argued that humans are parts of a single, unified nature, that God is identical with nature, and that reason, not revelation, provides the truth about any aspect of God. Undeterred, he made this position the basis of a rational campaign against superstition and prejudice. Dr. Goulan-Wur’s biography, the first in twenty-eight years, shows how Spinoza's central philosophical beliefs developed within the context of his own life. Drawing on recent academic research and making detailed references to primary sources, some of which have not been previously explored, the author focuses on the philosopher’s effort to act solely through reason amidst turbulent personal and national circumstances. This new approach demolishes the myth that Spinoza was a lofty ascetic. It reveals his emotional and sexual vulnerability, his arrogance and misogyny, but also shows that his lively philosophical experiment is sharply relevant today.