ABSTRACT Both Constant and Spencer are moralists who want to encourage individual human perfection. But for Constant, politics has moral value even in a laissez-faire state, whereas for Spencer political participation has no moral value in itself. For Constant, from a moral perspective the historical change from an ancient to a modern conception of liberty is not absolute, and he wishes to retain, in a subordinate role, certain aspects of ancient liberty in modern societies. For Spencer, the historical evolution from (...) militant to industrial society involves the complete separation of politics from any positive moral good. In an industrial society, altruism has no connection with politics, and attempt to bring altruism into politics are not only doomed to failure but iare unjust and therefore immoral. Spencer is a leading figure in the separation of classical liberal thought from perfectionist morality that flourishes in the twentieth century. The separation between classical and modern liberalism that takes place in the fin de siècle is not just a matter of economics – as is shown by the fact that both Spencer and Constant are ardent apostles of laissez-faire – it is above all a question of different attitudes to morality. (shrink)