And with this we are brought to a well-known and much-debated question. Is there a causal connection between the physical and the psychical, and are we to say that one series influences the other? I will begin by stating the view which prima facie suggests itself, I will then briefly discuss some erroneous doctrines, and will end by trying to set out a defensible conclusion. And, first, the belief which occurs to the unbiassed observer is that soul acts upon body and body on soul. I do not mean by this that bare soul seems to work on bare body, for such a distinction is made only by a further reflection. I mean that, if without any theory you look at the facts, you will find that changes in one series (whichever it is) are often concerned in bringing on changes in the other. Psychical and physical, each alike, make a difference to one another. It is obvious that alterations of the soul come from movements in the organism, and it is no less obvious that the latter may be consequent on the former. We may be sure that no one, except to save a theory, would deny that in volition mind influences matter. And with pain and pleasure such a denial would be even less natural. To hold that now in the individual pleasure and pain do not move, but are mere idle accompaniments, to maintain that never in past development have they ever made a difference to anything—surely this strikes the common observer as a wilful paradox. And, for myself, I doubt if most of those, who have accepted the doctrine in general, have fully realized its meaning.
This natural view, that body and soul have influence on each other, we shall find in the end to be proof against attack. But we must pass on now to consider some opposing conclusions. The man who denies the inter-action in any sense of body and soul, must choose from amongst the possibilities which remain. He may take the two series as going on independently and side by side, or may
