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] animal telephone system. It could create no energy--it could merely redirect the currents actually flowing.