parsimony and discipline which such a theory involves are balanced by the immense extension and certitude it gives to knowledge. It is at once an act of allegiance to nature and a Magna Charta which mind imposes on the tyrannous world, which in turn pledges itself before the assembled faculties of man not to exceed its constitutional privilege and to harbour no magic monsters in unattainable lairs from which they might issue to disturb human labours. Yet that spontaneous intelligence which first enabled men to make this genial discovery and take so fundamental a step toward taming experience should not be laid by after this first victory; it is a weapon needed in many subsequent conflicts. To conceive that all nature makes one system is only a beginning: the articulation of natural life has still to be discovered in detail and, what is more, a similar articulation has to be given to the psychic world which now, by the very act that constitutes Nature and makes her consistent, appears at her side or rather in her bosom.
That the unification of nature is eventual and theoretical is a point useful to remember: else the relation of the natural world to poetry, metaphysics, and religion will never become intelligible. Lalande, or whoever it was, who searched the heavens with his telescope and could find no God, would not have found the human mind if he had searched the brain with a microscope. Yet God existed in man’s apprehension long before mathe-