If this seems paradoxical it is, I think, mainly for two reasons. In the first place, such a doctrine seems inconsistent with the fact that, whatever Laplace’s calculator could do, humbler beings like ourselves manage somehow or other to forecast the behaviour of our neighbours with some small measure of success. This, no doubt, is true. But it is in part because the alternatives of behaviour are very few and very definite compared with the infinitely graduated variations of thought, will, and feeling. Action is “canalised.” It can flow only along channels engineered for it by circumstances, and among these the choice is commonly small. But the character which lies behind action is complex beyond all power of analysis, and variable beyond all powers of anticipation. The routine which is unwaveringly pursued from month to month and year to year is pursued each day in a different spirit: and often a critical hour strikes when some well-drilled creature of custom, to his own surprise and the scandal of his friends, deserts the ancient ways and wanders suddenly forth into the unknown. Of course, these violent aberrations are the exception. The more familiar experience is that, in an orderly society, the alternatives of action which need be taken into account are few, and the “limits of deviation” narrow. Often, therefore, we can anticipate conduct without any real insight into the depths of character or the complexities of motive from which the conduct springs. And truly this is fortunate; for, if mutual comprehension were necessary to social intercourse, how could society exist? But there is another reason why we take little note of the distinction I am endeavouring to draw between the calculable uniformities of a material world and the incalculable regularities of psychic life. The distinction is rather speculative than practical. It does not affect the routine of daily existence. For, although the course of the material world is calculable, we mortals have neither the time nor the knowledge nor the mental powers required to calculate it. We behave, therefore, towards nature as we behave towards man. We content ourselves with approximations, with analogies, with resemblances. Even if we had the power, we should not have the time to resolve the movement of all the bits of matter with which we have to deal from minute to minute into the exact sequences of which they are composed. We would not if we could. We apply rough methods; we are satisfied with imperfect results. Nor are these results always more imperfect in the psychic than in the material sphere of observation. The ways (for example) of British weather are even more mysterious than the ways of British men. Why, then, should we interest ourselves in a speculation which tells us, however truly, that perfect foreknowledge is theoretically possible in the first case, but theoretically impossible in the second? In practice it is impossible in both. And with this we must be content.