are descended from the lost ten tribes of Israel. Nevertheless, non-Euclidean geometry is not nonsense. In these circumstances it is probably fortunate that there are people patient enough to prepare careful and reasoned refutations of any whimsy that anybody cares to put forth. The extraordinary predisposition of the learned towards concocting merely silly theories must always be borne in mind. Studious persons often have a very small range of experience of life; they have nothing like so broadly based a sense of probability as the ordinary man of the world possesses, which is why so many of them seem curiously innocent and gullible. The beaming and genial professor expounding his theory often seems curiously like a child playing with toys. The mixture of amusement and respect with which the world watches him is, on the whole, the correct reaction. As long as he is dealing with the incomprehensible one may grant him authority. Nobody dreams of questioning astronomical pronouncements about forthcoming eclipses. But when he is talking about the very stuff of our ordinary experience, as in psychology, we do wrong to accept the obviously absurd for fear that it cannot be as silly as it looks. A great deal of what is called psycho-analysis, for instance, is merely silly. Only people singularly deficient in common-sense and completely lacking in a sense of humour could have invented anything so preposterous. Undoubtedly some pathological states are of sexual origin, but the lengths to which the theory has been carried and the kind of interpretations that are given make the development of psycho-analysis one of the greatest psychological curiosities of our time. Whole-hearted belief in psycho-analysis certainly points to the existence of a complex. As with any other complex, it is defended by arguments to which none except those who are similarly afflicted can attach the slightest validity. The complex is strongly materialistic, not in the sense that everything is reduced to “matter and motion”, but in the sense that the lowest human activities are made explanatory of all the rest. One often finds, associated with a belief in materialism, a desire to deny any form of spiritual excellence. The ostensible motive is simplification, as when material substances are reduced to a small number of chemical elements; but it is usually obvious, from the forced explanations that are attempted, that the real motive is something very different. Much, of course, must be attributed to insensitiveness, as we see when we turn to psycho-analytic explanations of works of art. The extraordinary force of the psycho-analysts’ complex is well shown by the sort of arguments they find convincing. Thus they may profess to show that artistic tastes never exist without suppressed sexual desires. Their way of establishing this fact, which is chiefly by asserting it, is comparatively rational. But they then proceed to the statement that a