The Tractatus Theologico-politicus was published anonimously in 1670, thereby challenging a moderately tolerant Dutch Republic (Pierre Bayle’s great arch of the refugees). The defence of libertas philosophandi (freedom of speech and thought) put forward by Spinoza, along with the underlying analysis of the fundamentals of religion and political power, were received as a radical proposal in Modern Europe, though despite prompting severe criticism and considerable amount of refutations, it circulated profusely and was translated into French, English and Dutch before the end of the century. This volume analyzes into detail Spinoza’s line of reasoning, identifies its allies and its enimies, explores its more or less obvious connections with the Ethica, in order to shed light and reasess the value of this indispensable classic of theological and political thought for our time.