Of the state of thought in our own country we may fairly say that a generation ago opinion on the ultimate questions was, in the main, fairly divided into two camps. There were the professional metaphysicians, mainly living on a tradition derived from Kant and Hegel, and there were the men of science whose 'philosophy', such as it was, is perhaps best represented by two well-known and most instructive books, Mach's _Science of Mechanics_ and Karl Pearson's _Grammar of Science_. The men of the Kant-Hegel tradition, whatever their family dissensions, were generally united by the common view that--as William James accused them of teaching--the function of sensation in contributing to knowledge, whatever it is, is something 'contemptible'. Kant himself, as we have seen, had thought very differently, but he was supposed to have been 'corrected' on this, as on so many points, by Hegel. The most distinguished of my own Oxford teachers seemed agreed to believe that our thought builds up the fabric of knowledge entirely from within by what Hegel called an 'immanent dialectic'. A rough idea of what this means may be given in the following way. You take any experience you please and try to put what you experience into a proposition. The proposition may, to begin with, be as vague as, e.g. 'I am now feeling something,' 'I am now aware of something.' On reflection you find that the statement does not do justice to the experience. You feel the need to say more precisely _what_ you are feeling or are aware of, how it is related to what you experience on other occasions, and what the 'I' is which is said to 'have' the experience. Until you have done this your thought is a miserable reproduction of your experience, and if you could ever do it completely, it would turn out that a really adequate account of the most trivial experience would involve complete knowledge of the structure and working of everything. Thus, if you once begin to think about your experience at all, you are irresistibly driven on to endless further reflection. If you try to stop short anywhere in the process, the results of your reflection are found to contain unexplained contradictions, just because you have not yet fitted on the fact on which you are reflecting to everything else there is to know. All the assumptions of every-day 'common sense' and all the more recondite assumptions of the sciences are saturated with these contradictions, because both 'common sense' and the sciences leave so much of the whole 'story of everything' untouched. If the whole story were told, all things would be found to be just one thing, which these philosophers call the 'Absolute', and the only perfectly true statement we can make would be a statement about this Absolute in which we asserted of it all that it is. Since no science ever attempts to say anything at all about this one sole thing, far less to get all there might be to be said about it into a single statement, no scientific