The future is uncertain. But that is no reason why you should be. There is no evidence that we shall succeed, that logic can be trusted, or that science is true. But fortunately it is possible to be certain without evidence. In commenting on the text "Faith is the assurance of things hoped for, the proving of things unseen," Professor Huxley says, "I fancy we shall not be far from the mark if we take the writer to have had in his mind the profound psychological truth, that men constantly feel certain about things for which they strongly hope, but have no evidence, in the legal or logical sense of the word; and he calls this feeling 'faith.'"[36] It is a profound psychological truth, and by the aid of the theory of evolution we may understand why it is so deep-seated in the mental and moral constitution of man. Primitive man can have had no extensive "evidence" of any kind to go upon in regulating the conduct of his daily life; and in all probability exercised but little power of criticism in judging the value of what evidence he had. At the same time, if he was to survive at all in the struggle for existence, he had to act and to act promptly. Fortunately for him it was possible to feel certain about things for which there was no evidence, _i.e._ to have faith. And he survived in consequence--in virtue of the law of the survival of the faithful, a law whose operation is possibly not confined to this world. On the theory of evolution, again, man's wants must have aided him in the struggle for existence; and no evolutionist will doubt that the desire to be rational and to do that which is right has assisted man in his upward struggle. The victory has remained with those who have been contented to feel certain about things for which they had no evidence, and to act on faith. It is those who hesitate to do right until sacrifice of self is proved to be reasonable, who lose their chance, and consequently have been and are being, though slowly, weeded out. Those who have yielded to their inner impulse to believe, without evidence, have evidently been the better fitted to their environment, and the more in harmony with the ruling principle of the cosmos and its evolution.