terminology of the schools, and employs the language current in the better kinds of ordinary literature and the well-bred society of his time.' In fact, as was said of Socrates, he brought philosophy down from heaven to earth; and this service, and the great influence which his work produced upon the future development of philosophy, are perhaps stronger claims to permanent distinction than the merits of a theory which can never be overlooked, but can never again command the almost universal assent which it received in its own day. For the application of physiology to psychological research, implicitly, at all events, advocated by Locke, has produced results of which neither he nor his opponents dreamed. The central point of his philosophy is the denial of innate ideas; the mind is to him a _tabula rasa_, a sheet of blank paper, and all the ideas which have been thought inherent in it are the result of experience. In a sense we now know this to be true; but we also know this experience not to be the experience of the individual, but of the race, or rather say of sentient existence for ages inconceivably remote. It follows that although Locke may be abstractedly right in denying the possibility of the acquisition of ideas except through experience, yet practically everyone comes into the world with a host of ideas derived from his ancestors, connate if not innate; and that, so far from the human mind resembling a sheet of blank paper, it is more like a palimpsest inscribed and reinscribed _ad infinitum_. It also follows that the discrepancies of mankind respecting points of morality do not, as Locke thought, disprove the existence of an ideal rule of right, for everyone must necessarily be born with inherited instincts by which such a rule is more or less deflected or obscured. In fact, Locke and his adversaries were both partly right and partly wrong--one party in denying intuition, the other in defining it. Neither had found, or at that period could have found, the real key to the difficulty; but it is to the immortal honour of Locke that all real advance in psychology has been effected by working in his spirit of observation and induction, rather than by the _à priori_ method of his opponents. The third and fourth books of the essay, _On Words_ and _On Knowledge_, contain but little controversial matter, and are chiefly devoted to illustrating the imperfection of human faculties, especially language, the necessity for clear and definite conceptions, and the countless impediments in the way of truth.