Voltaire is one of the greatest thinkers of the eighteenth century—a poet, playwright, publicist, and historian. He was called the “king of public opinion.” In his sharp articles and pamphlets, Voltaire protested against wars, religious fanaticism, persecution of dissenters, and spoke in favor of education and social freedoms. “A Treatise on Tolerance,” written two and a half centuries ago, sounds fresh and urgent even today, since its main theme—tolerance for dissenters—is relevant at all times. The author believes tolerance is one of the fundamental principles of humanity and calls on us to follow this principle in our actions.