Abstract
When I agreed to lecture to-night I stipulated that I might be allowed to interpret the subject announced so as to let my treatment relate less to the subject in general than to some particular aspects which happen to have been interesting me lately. Professor Whitehead, Sir Arthur Eddington, and Sir James Jeans have given to the world brilliant accounts of the present position of physics in relation to mathematics and philosophy. What I have to say bears to their writings, the humble relation of an example to a piece of book-work, or of an application of a theorem to the theorem itself.