"... the dialogue between mathematical physics, geometry, and algebraic topology. The interaction between these subjects has been such a dominant feature of research developments in the past few years that it seems scarcely necessary to recite a list of examples: in fact, on the mathematical side it is quite hard to think of active areas in geometry and topology which have not been noticeably influenced by insights from physics—where by "physics" we mean particularly quantum field theory—and on the other hand the geometrisation of fundamental physical concepts is a profound and pervasive development."