Treatise on Tolerance (1763), born of Voltaire's campaign to overturn the wrongful execution of the Protestant Jean Calas, moves from a tightly argued case brief to a meditation on fanaticism and civil concord. In lucid, ironical prose, it splices historical episodes and comparative religion with appeals to experience and natural right, advancing freedom of conscience and legal restraint. A cosmopolitan deist seasoned by English exile, censorship, and the vast correspondence he directed from Ferney, Voltaire turned indignation into method. His admiration for English toleration, consultations with jurists, and orchestration of witnesses and public opinion in the Calas affair shaped the book's evidentiary rigor and strategic irony; Calas's posthumous rehabilitation confirmed his faith in enlightened opinion. Scholars of law, religion, and political thought will find a classic of public reasoning-accessible, learned, and morally urgent. For readers confronting contemporary pluralism and punitive zeal, this concise plea for tolerance remains bracingly relevant, a humane antidote to dogma and a primer in civic courage. Quickie Classics summarizes timeless works with precision, preserving the author's voice and keeping the prose clear, fast, and readable-distilled, never diluted. Enriched Edition extras: Introduction · Synopsis · Historical Context · Author Biography · Brief Analysis · 4 Reflection Q&As · Editorial Footnotes.