Art is a great thing. But it is not the greatest. The most important of all perceptions is the continual perception of cause and effect — in other words, the perception of the continuous development of the universe — in still other words, the perception of the course of evolution. When one has thoroughly got imbued into one’s head the leading truth that nothing happens without a cause, one grows not only large-minded, but large-hearted.

It is hard to have one’s watch stolen, but one reflects that the thief of the watch became a thief from causes of heredity and environment which are as interesting as they are scientifically comprehensible; and one buys another watch, if not with joy, at any rate with a philosophy that makes bitterness impossible. One loses, in the study of cause and effect, that absurd air which so many people have of being always shocked and pained by the curiousness of life. Such people live amid human nature as if human nature were a foreign country full of awful foreign customs. But, having reached maturity, one ought surely to be ashamed of being a stranger in a strange land!

The study of cause and effect, while it lessens the painfulness of life, adds to life’s picturesqueness. The man to whom evolution is but a name looks at the sea as a grandiose, monotonous spectacle, which he can witness in August for three shillings third-class return. The man who is imbued with the idea of development, of continuous cause and effect, perceives in the sea an element which in the day-before-yesterday of geology was vapour, which yesterday was boiling, and which to-morrow will inevitably be ice.

He perceives that a liquid is merely something on its way to be solid, and he is penetrated by a sense of the tremendous, changeful picturesqueness of life. Nothing will afford a more durable satisfaction than the constantly cultivated appreciation of this. It is the end of all science.

Cause and effect are to be found everywhere. Rents went up in Shepherd’s Bush. It was painful and shocking that rents should go up in Shepherd’s Bush. But to a certain point we are all scientific students of cause and effect, and there was not a clerk lunching at a Lyons Restaurant who did not scientifically put two and two together and see in the (once) Two-penny Tube the cause of an excessive demand for wigwams in Shepherd’s Bush, and in the excessive demand for wigwams the cause of the increase in the price of wigwams.

“Simple!” you say, disdainfully. Everything — the whole complex movement of the u............