The most important general remedy for over-prolonged mental occupation with a single subject, is some outdoor sport or form of exercise that requires all the attention. Horseback exercise is particularly valuable; boating, especially where the man has charge of the boat himself and where he has to have his wits about him, and the various sports. It is particularly important that men should not be alone during the taking of their exercise and diversion of mind. Above all, human interests take a man outside of himself and keep him from disturbing his mental equipoise by too much devotion to a single subject.