Left, Revolution, Proletariat–these fashionable concepts are the latter-day counterparts of the great myths which once inspired political optimism: Progress, Reason, the People. The myth of the Left presupposes the myth of Progress; it retains the historic vision of the latter, though without the same confidence–for the Left cannot help but find itself confronted with a Right which bars its way and is never conquered or converted. The Left is the party which refuses to resign itself to injustice and which maintains, against the equivocations of authority, the rights of the free conscience. The historical experience of the twentieth century reveals the frequency and the causes of revolutions in the industrial age. The sequence of the Reformation, the bourgeois Revolution and the social Revolution may be interpreted in terms of the Germany of the sixteenth century, the France of the eighteenth and the Russia of the twentieth as the successive instruments of Reason.