The notion that we live in a purposeless universe is so opposed to the mental habits we have inherited that it is a matter of the greatest difficulty to bear it constantly in mind. Most of the people who hold this belief to-day would not do so but for three reasons: the disillusionment caused by the War, their respect for science, and their belief that science preaches materialism. As for the War, that is an experience to which we must accommodate ourselves as best we may. It is consistent with the belief that man is a developing spirit, but it is certainly a proof that he is not very far developed. The respect for science is, I believe, on the whole rather overdone. The respect is a little excessive even when it relates to mathematical physics, but it becomes almost absurd when it relates to some other branches of science. I believe, for instance, that Freud’s form of psycho-analysis, some forms of behaviourism, and many of the statements of the eugenists really are as silly as they look. All that they have in common with such first-class mental activities as physics and chemistry is the name “science.” It is this name that secures for them such attention as they get from intelligent people who are not cranks. But even physics is a more provisional and more human thing than some romantic references to it would lead one to suppose. Even the tower of the mathematician, which Mr Bernard Shaw imagines to have been always unshaken, has been seriously disturbed on more than one occasion. The student of the history of science will not be too confident even of the “indubitable certainties” of physics when he reflects on the universal passion of belief that attached to the notion of a mechanical ether, for whose present absence from the universe some men of science are still inconsolable, and when he reflects on the fate that has overtaken that “most perfect and perfectly established law”, Newton’s law of gravitation. There are no indubitable certainties in science, a fact that we who are contemporary with the destruction of the Newtonian system are not likely to forget. There are only provisional hypotheses. It may even be, as Mr J. B. S. Haldane prophesies, that physiology will one day invade and destroy mathematical physics, by which somewhat dark saying I suppose phenomena mathematically may be given up. Whether he means that or not, it is a possibility, as Professor Eddington has hinted. The scientific practitioner usually treats his hypotheses as tools, but to the layman they become dogmas. One is led to believe this by seeing that many of those who accept materialism on what they suppose to be scientific evidence are rendered acutely unhappy by their belief. A truer knowledge of the status of scientific theories would render this agony unnecessary. There are people with a natural leaning towards materialism, and science, preferably somewhat old-fashioned science, will give them quite sufficient grounds to indulge their