do so, however, it is needful to go back to its real founder, Locke, in order that its point of view may fairly be set forth.
In applying his mind to the views of Locke, the ordinary man finds himself arriving at very commonplace and well-accustomed conceptions. Locke, indeed, may reasonably be said to represent the ideas of common, everyday life. The ordinary man does not question the reality of things, he accepts it without asking any questions, and bases his theories—scientific or otherwise—upon this implied reality. Locke worked out the theory which had been propounded by Lord Bacon, that knowledge is obtained by the observation of facts which are implicitly accepted as realities; and what, it was asked, could be more self-evident and sane? It is easy to conceive a number of perceiving minds upon the one hand, ready to take up perceptions of an outside material substance upon the other. The mind may be considered as a piece of white paper—a tabula rasa, as it was called—on which external things may make what impression they will, and knowledge is apparently explained at once. But though Locke certainly succeeded in making these terms the common coin of ordinary life, difficulties crop up when we come to examine them more closely. After all, it is evident, the only knowledge our mind can have is a knowledge of its own ideas—ideas which are, of course, caused by something which is outside, or at least, as Locke would say, by its quality. Now, from this it would appear that these 'ideas' after all come between the mind and the 'thing,' whatever it is, that causes them—that is to say, we can perhaps maintain that we only know our 'ideas,' and not things as in themselves. Locke
