ay, the
association may be one which it is necessarily beyond the power of
the human mind to explain.

So far as I can see, this list of possible answers to the question
before us is exhaustive. I will next show why, in my opinion, the last
four of them may be excluded _in limine_.

The suggestion of pre-established harmony (IV) merely postpones the
question: it _assumes_ a higher _mind_ as adjusting correspondencies
between known minds and animal bodies with respect to the activities of
each; and, therefore, it either leaves untouched the ultimate question
concerning the relation of mind (as such) to matter, or else it answers
this question in terms of spiritualism (I).

The suggestion of chance (V) is effectually excluded by the doctrine of
chances: even in any one individual mind, the association between mental
changes and material changes is much too intimate, constant, and
detailed to admit of any one reasonably supposing that it can be due
only to chance.

The suggestion of pure idealism (VI) ultimately implies that the
thinking Ego is itself the sole existence--a position which cannot,
indeed, be turned by any assault of logic; but one which is
nevertheless too obviously opposed to common sense to admit of any
serious defence; its immunity from direct attack arises only from the
gratuitous nature of its challenge to prove a negative (namely, that the
thinking Ego is _not_ the sole existence), and this a negative which is
necessarily beyond the region of proof.

Lastly, the suggestion that the problem is necessarily insoluble (VII)
does not deserve to be regarded as an hypothesis at all; for to suppose
that the problem is necessarily insoluble is merely to exclude the
supposition of there being any hypothesis available.

In view of these several considerations, it appears to me that, although
in a formal sense we may say there are altogether seven possible answers
to the question before us, in reality, or for the purposes of practical
discussion, there are nowadays but three--namely those which head the
above list, and which I will now proceed to consider.

I have named these three hypotheses in the order of their appearance
during the history of philosophical thought. The earliest is the
spiritualistic. As far back as we can trace the conceptions of primitive
man, we meet with an unquestioning belief that it is his spirit which
_animates_ his body; and, starting from this belief as explanatory o