This principle has manifold illustrations. The hand or muscle disused withers in power. The fishes of the Mammoth Cave, having no use for their eyes, lose them. Mr. Darwin in an impressive passage of his biography testifies that he began life with a taste for poetry and music, but that by disuse this aesthetic taste grew atrophied so that at last he did not care to read a poem or to hear a musical note. So it is, says Jesus, with spiritual insight and power. Sometimes we see a man of intellectual {137} gifts lose his grasp on spiritual realities, and we ask: "How is it that so learned a man can find little in these things? Does not he testify that these things are illusions?" Not at all. It is simply that he has not kept his life trained on that side. His capacity has been extirpated by disuse. He may know much of science or language, but he has lost his ideals. We hear a young man sometimes say that he has grown soft by lack of exercise. Well, if you live a few years you will see people who have grown soft in soul, and you will see some great blow of fate smite them and crush them because their spiritual muscle is flabby and weak. Ignatius Loyola laid down for his followers certain methods of prayer which he called "Spiritual Exercises." So in one sense they were. They kept souls in training. The exercise of the religious nature is the gymnastics of the soul, and the disuse of the religious nature extirpates its capacity. That is the solemn ending of the parable of the talents. From him who does not use his power there is taken away even the power that he hath. {138} LVI THE PARABLE OF THE VACUUM _Matthew_ xii. 38-45. It is easy to see where the emphasis of this parable lies. It is on the impossible emptiness of this man's house. A man casts out the devil of his life and turns the key on his empty soul and feels safe. But he cannot thus find safety. That is not the way to deal with evil spirits. Back they come, crowding into his life through the windows if not through the doors, and the last state of that man is worse than the first. If the parable had been told in modern times it might have been called the parable of the vacuum. A man's life is a space which refuses to be empty. If it is not tenanted by good the evil knocks and enters it. There is no such thing as an unoccupied life. Nature abhors a vacuum.