This is one of the most important essays in the Marxist tradition which seeks to recapture philosophy from the empyrean and restore it to history. The “purity” of philosophy, Nizan writes, “Is purely imaginary. Every philosopher – though he may consider himself unsullied – participates in the impure reality of his age.” Thus this book is the Marxist counterpart of such works in the field of sociology as Lynd’s knowledge for What? And Mills’ the Sociological Imagination.