It was the biologists of the nineteenth century, intoxicated with the delusion that the magic word evolution was a key to unlock all the mysteries of the universe, who foisted on the world the idea that man is but a complicated physical and chemical machine, and who sought to discredit the dualistic philosophy of the Renaissance physicists. And of all the biologists, Huxley, the militant propagandist, was the one who did the most to degrade humanism into the pseudo-sciences of psychology and sociology. He first correctly emphasised the fact that there is but one scientific method which is best exemplified by the subject of mechanics. But--and in this lies the source of his mischief to clear thinking--_he then defined science as merely organised common sense_. One has only to analyse this definition to discover its speciousness and its confusion of thought. His definition has been almost universally accepted, although it undoes all the lessons taught us by the religious thinkers of the Middle Ages and the scientific experimentalists of the Renaissance; and its effect has been to drive theoretical science back into the hypothetical metaphysics of the Greeks. It is merely a truism to say that our contact with the objective and subjective worlds is based, directly or indirectly, on our sense-perceptions; and, to be intelligibly transmitted from one person to another, such data must be common to many individuals. Also, it is an inevitable tendency of the mind to organise all facts or to link them together. Thus Huxley really classes all sound knowledge as science. But, since this sound knowledge, according to him, can be attained only by following the method of mechanics, which is the interpretation by the mind of the spatial and temporal relations between sensible bodies, his inference is clear that the phenomena of consciousness, the individual mind, and our social relations, are to be interpreted as problems of matter and motion. Yet what, actually, is the process of exact science? The answer to this question should show us whether or not the term does have any precise and limited significance, and whether or not fundamental confusion must result from the attempt to make it synonymous with all knowledge.