existing conditions that can never be completely known until we have mastered the whole series of physical phenomena, and showed that all human induction is fallible because necessarily imperfect, it became clear that Mill had very little to offer in substitution for those grounds of ordinary belief that he was bent on demolishing. The word Cause is reduced, for ordinary use, to a signification not unlike that which is understood in loose popular language by the word Chance, since Chance means no more than ignorance of how an event came to pass; and in no case, according to Mill, can we ever calculate with security what undiscoverable conditions may suddenly bring about an unexpected event contrary to previous experience. The uniformity of Nature, as Mr. Stephen remarks, is thus made exceedingly precarious; and to the practical intelligence, which looks for some basis that cannot be argued about, there is still something to be said for Intuition. And when Mill, still in search of some precise formula, undertook to interpret persistent sequences by his theory of Real Kinds possessing an indeterminate number of coherent properties--so that our belief in the invariable blackness of crows is justified as a collocation of these visible properties--he merely throws the problem of Causation farther backward. We have to be content with direct observation of phenomena that can be classified as co-existent; we can perceive that things accompany each other, but we can never be sure that they follow each other, as they appear to do. It may be doubted whether Mill's treatment of these problems has materially affected subsequent psychological speculation, which has since taken different and deeper courses. His main objective was social and political. 'The notion,' he has written, 'that truths external to the mind may be known by intuition, or consciousness, independently of observation and experience, is, I am persuaded, in these times the great intellectual support of false doctrines and bad institutions.' In confounding the metaphysicians, and eliminating all mysterious assumptions or axioms, he aimed at clearing the ground for a demonstrable science of character, and to establish the great principle that character can be indefinitely modified. The way is thus opened to questions of conduct, to positive remedies for social and political evils which, as they have been generated and fostered by external circumstances, can be removed by a change of those circumstances.