converged upon a single unit, a gland at the base of the brain. In this
unit, or in the convergence of all the motions upon it, the 'unity' of the
body virtually consisted; and the soul was incarnate, not in the plurality
of members (for how could it, being one, indwell many things?), but in the
single gland.

Even so, the relation between the soul and the gland was absolutely
unintelligible, as Descartes disarmingly confessed. Incarnation was all
very well in the old philosophy: those who had allowed the interaction of
disparate natures throughout the physical world need find no particular
difficulty about the special case of it provided by incarnation. Why should
not a form of conscious life so interact with what would otherwise be dead
matter as to 'indwell' it? But the very principle of the new philosophy
disallowed the interaction of disparate natures, because such an
interaction did not allow of exact formulation, it was a 'loose' and not a
'tight' relation.

From a purely practical point of view the much derided pineal gland theory
would serve. If we could be content to view Descartes as a man who wanted
to make the world safe for physical science, then there would be a good
deal to be said for his doctrine. In the old philosophy exact science had
been frustrated by the hypothesis of loose relations all over the field of
nature. Descartes had cleared them from as much of the field as science was
then in a position to investigate; he allowed only one such relation to
subsist, the one which experience appeared unmistakably to force upon
us--that between our own mind and its bodily vehicle. He had exorcized the
spirits from the rest of nature; and though there was a spirit here which
could not be exorcized, the philosophic conjurer had nevertheless confined
it and its unaccountable pranks within a minutely narrow magic circle: all
mind could do was to turn the one tiny switch at the centre of its [20]