This paper shows how reflection on habit leads in nineteenth-century French philosophy to Henri Bergson’s idea of duration in 1888 as a non-quantifiable dimension irreducible to time as measured by clocks. Historically, I show how Albert Lemoine’s 1875 L’habitude et l’instinct was crucial, since he holds – in a way that is both Ravaissonian and Bergsonian avant la lettre – that for the being capable of habit, the three elements of time are fused together. For that habituated being, Lemoine claims, (...) it is not true to say that the past is no longer, nor even that the future is not yet. This historical link between Ravaisson and Bergson, however, only sharpens the philosophical question of how a dynamic conception of habit involves and requires a conception of real duration, of a temporality more original than clock-time, and, conversely, of how reflection on duration prior to clock-time involves a notion of habit. With reference to the work of Gilles Deleuze, the paper concludes by showing that there is an internal connection between these two grand philosophical themes of nineteenth- and then twentieth-century French thought: habit and time. (shrink)