and to its effective environment. What Descartes had
really done was to pretend that the soul was related to the pineal gland as
it is in fact related to its whole body; and then that it was related to
the bodily members as in fact it is related to outer environment. The
members became an inner environment, known only in so far as they affected
the pineal gland; just as the outer environment in its turn was to be known
only in so far as it affected the members.

[21]
This doctrine of a double environment was wholly artificial. It was forced
on Descartes by the requirements of mechanistical science: if the members
were simply a plurality of things, they must really be parts of
environment; the body which the soul indwelt must be _a_ body; presumably,
then, the pineal gland. An untenable compromise, surely, between admitting
and denying the reality of the soul's incarnation.

What, then, was to be done? Descartes's rivals and successors attempted
several solutions, which it would be too long to examine here. They
dissatisfied Leibniz and they have certainly no less dissatisfied
posterity. It will be enough for us here to consider what Leibniz did. He
admitted, to begin with, the psychological fact. The unity of consciousness
is the representation of a plurality--the plurality of the members, and
through them the plurality of the world. Here, surely, was the very
principle the new philosophy needed for the reconciliation of substantial
unity with mechanical plurality of parts. For it is directly evident to us
that consciousness focuses the plurality of environing things in a unity of
representation. This is no philosophical theory, it is a simple fact. Our
body, then, as a physical system is a mechanical plurality; as focused in
consciousness it is a unity of 'idea'.

Very well: but we have not got far yet. For the old difficulty still
remains--it is purely arbitrary, after all, that a unitary consciousness
should be attached to, and represent, a mechanical collection of things
which happen to interact in a sort of pattern. If there is a consciousness
attached to human bodies, then why not to systems of clockwork? If the body
is _represented_ as unity, it must surely be because it _is_ unity, as the
old philosophy had held. But how can we reintroduce unity into the body
without reintroducing substantial form, and destroying the mechanistical
plurality