Alain (Émile Chartier) taught him; Sartre, Nizan and Aron were fellow-students. Cavaillès encouraged him to join the resistance during WWII. Bachelard taught alongside him. Deleuze and Bourdieu studied under him; he sponsored Foucault’s doctoral thesis on the history of madness, and advised Derrida to establish himself seriously before indulging in intellectual humour. Althusser declared that his debt to Canguilhem was incalculable.