The subject on which I am to address you this evening is one which, though it is of fundamental importance both for philosophy and for practice, cannot but present the gravest difficulties for such treatment as falls within the limits of this occasion. Philosophical problems are always difficult, but those of ultimate metaphysics are in this respect egregious. For the simplifications that are open to the scientific phenomenologist who can rest content with a spatiotemporal world, or to the analyst who concentrates on the objective content with which the human understanding most conspicuously concerns itself, are not open to the metaphysician. He must meet the full complexity of things: not limiting himself to their appearances as objects within human experience, nor to a reflective analysis of their objective content, but taking them as they must be in themselves in order that they may appear as they empirically and reflectively do appear for the special cognitive faculties of man. I ask, therefore, for your patience and attention as I try first of all to lead you into, and then, as I hope, out of, the metaphysical labyrinth. For what I have to describe is something of a metaphysical adventure, or, if you like, a metaphysical ghoststory, in which the ghosts assume such reality as to make the solid things “give up the ghost”—which is just as it should be in a good ghost-story!