What do we know that van der Waals did not know?

Reference is made to some of the areas in which van der Waalsʹs work in the nineteenth century anticipated modern developments. This includes applications of the mean-field approximation to the study of dense liquids, of critical phenomena in pure and multicomponent fluids, and of higher-order critical points, particularly tricritical points. The main focus of this lecture, though, is on interfacial structure and thermodynamics, where the work of the present author has had its roots in van der Waalsʹs theory of capillarity. Problems treated include those of wetting and line tension in three-phase equilibrium; pre- (or premonitory) wetting and premelting (surface melting) and the associated boundary tension in the interface between bulk phases; and fluctuations in the internal composition of interfaces and three-phase lines.