One theme in Leo Strauss's work is so salient that it seems almost too obvious to remark, yet its salience in his thought stands in sharp contrast with its near disappearance from so much of modern philosophy. That theme is the conception of philosophy as a way of life, and the related claims that the character of this way of life and its choice or justification as the right way of life are themselves major themes of philosophy, even the major themes of Socratic philosophy or, as Strauss would have it, classical political philosophy. This conception contrasts with the conventional contemporary academic conception of philosophy as a discipline (a discipline in the sense of a branch of research with its own methods and subject matters, rather than as askesis or formation of character).

In Natural Right and History Strauss introduces “the idea of philosophy” in his discussion of conventionalism, a particular form of classical philosophy, early in the first chapter, “Natural Right and the Historical Approach.” Following Plato's famous metaphor in Book VII of the Republic, Strauss writes that philosophizing means “to ascend from the cave to the light of the sun, that is to the truth,” from “the world of opinion” to knowledge (11–12). This distinction between the worlds of opinion and knowledge is not only epistemological but social or political: the cave or world of opinion from which philosophy ascends is not private or individual opinion but public opinion, the authoritative opinion stabilized by the social fiat of a particular political community without which its members cannot live together. “Philosophizing means, then, to ascend from public dogma to essentially private knowledge.”