Lamarck's perspective on change within the organic world, in particular his conception of "la marche de la nature," , crystallized during the last decade of the 18th century and the early years of the 19th. I argue that it should be viewed as resulting in part from interactions with, and transfers from, the social thought—modes of thinking, ways of conceptualizing, models, metaphors and analogies—of the decades before the French revolution and of the revolutionary decade itself. Moreover, Lamarck's involvement with the (...) new institutional frameworks initiated during the revolutionary period had brought him into direct contacts with the then prevalent modes of discourse on things social. (shrink)