PEOPLE form habits which cause nervous strain. When these habits have fixed themselves for long enough upon their victims, the nerves give way and severe depression or some other form of nervous prostration is the result. If such an illness turns the attention to its cause, and so starts the sufferer toward a radical change from habits which cause nervous strain to habits which bring nervous strength, then the illness can be the beginning of better and permanent health. If, however, there simply is an enforced rest, without any intelligent understanding of the trouble, the invalid gets "well" only to drag out a miserable existence or to get very ill again.