This volume brings together the major contributions of J L Koszul and some expository articles. They are organized in chronological order.The main subjects included are: cohomology of Lie algebras; relative cohomology; reductive subalgebras and transgression theorem; the formalism of spectral sequences; “Koszul complexes”; proper and differentiable actions of Lie groups; slices; hermitian forms on complex homogeneous domains; bounded domains; locally flat manifolds; convex homogeneous domains; simplicial spaces; themes related to Gelfand Fuks theory and supergeometry.
