Tonight I propose to say something about a man who is now recognised as a pioneer mathematician of his time, but I do not intend to talk about his work as a creative mathematician. I shall leave that to others who are far better qualified to do so. As a young man I studied pure mathematics under Young and G. H. Hardy, but most of my work as a professional mathematician has been in mathematical physics, and I cannot say anything significant about subjects that I ceased to work on some thirty-five years ago.