Locke was a contemporary and friend of Newton; his great book, _An Essay concerning Human Understanding_, was published at almost the same moment as Newton’s _Principia_. His influence has been enormous, greater, in fact, than his abilities would seem to warrant; and this influence was not only philosophical, but quite as much political and social. He was one of the creators of eighteenth century liberalism: democracy, religious toleration, freedom of economic enterprise, educational progress, all owe much to him. The English Revolution of 1688 embodied his ideas; the American Revolution of 1776 and the French Revolution of 1789 expressed what had grown, in a century, out of his teaching. And in all these movements, philosophy and politics went hand in hand. Thus the practical success of Locke’s ideas has been extraordinary. When, knowing all this, one comes to read Locke himself, it is difficult to resist a feeling of disappointment. He is sensible, enlightened, minute, but uninspired and (to moderns) uninspiring. One has to remember that his contemporaries found common sense exhilarating after a century of wars of religion and a long struggle with obscurantism. Locke combatted the doctrine of “innate ideas”, according to which we learned only certain things by experience, but possessed our abstract knowledge in virtue of our congenital constitution. He regarded the mind at birth as a wax tablet, upon which experience proceeded to write. Undoubtedly he was, in this matter, more in the right than his opponents, although the terms in which the controversy was waged are not such as a modern could employ. We should say that the innate apparatus of man consists of “reflexes” rather than “ideas”; also that our sense-organs, our glands, and our muscles lead to responses of certain kinds, in which our own organisation plays a part of the same importance as that played by the external stimulus. The element in our knowledge-responses that corresponds to our own bodily organisation might, perhaps, be regarded as representing what Locke’s opponents meant by “innate”. But it does not represent this at all accurately so far as our feelings towards it are concerned. The “innate” ideas were the ideas to be proud of; they embraced pure mathematics, natural theology, and ethics. But nobody is proud of sneezing or coughing. And when Locke tried to show, in detail, how our knowledge is generated by experience, he was liberating philosophy from a great deal of useless lumber, even if his own doctrines were not altogether such as we can now accept.