Another cause of mental disease, is, the excessive exercise of the intellect or feelings. If the eye is taxed, beyond its strength, by protracted use, its blood-vessels become gorged, and the bloodshot appearance warns of the excess and the need of rest. The brain is affected, in a similar manner, by excessive use, though the suffering and inflamed organ cannot make its appeal to the eye. But there are some indications, which ought never to be misunderstood or disregarded. In cases of pupils, at school or at college, a diseased state, from over action, is often manifested by increased clearness of mind, and ease and vigor of mental action. In one instance, known to the writer, a most exemplary and industrious pupil, anxious to improve every hour, and ignorant or unmindful of the laws of health, first manifested the diseased state of her brain and mind, by demands for more studies, and a sudden and earnest activity in planning modes of improvement for herself and others. When warned of her danger, she protested that she never was better, in her life; that she took regular exercise, in the open air, went to bed in season, slept soundly, and felt perfectly well; that her mind was never before so bright and clear, and study never so easy and delightful. And at this time, she was on the verge of derangement, from which she was saved only by an entire cessation of all her intellectual efforts. A similar case occurred, under the eye of the writer, from over-excited feelings. It was during a time of unusual religious interest in the community, and the mental disease was first manifested, by the pupil bringing her Hymn-book or Bible to the class-room, and making it her constant resort, in every interval of school duty. It finally became impossible to convince her, that it was her duty to attend to any thing else; her conscience became morbidly sensitive, her perceptions indistinct, her deductions unreasonable, and nothing, but entire change of scene, exercise, and amusement, saved her. When the health of the brain was restored, she found that she could attend to the "one thing needful," not only without interruption of duty, or injury of health, but rather so as to promote both. Clergymen and teachers need most carefully to notice and guard against the danger here alluded to. Any such attention to religion, as prevents the performance of daily duties and needful relaxation, is dangerous, as tending to produce such a state of the brain, as makes it impossible to feel or judge correctly. And when any morbid and unreasonable pertinacity appears, much exercise, and engagement in other interesting pursuits, should be urged, as the only mode of securing the religious benefits aimed at. And whenever any mind is oppressed with care, anxiety, or sorrow, the amount of active exercise in the fresh air should be greatly increased, that the action of the muscles may withdraw the blood, which, in such seasons, is constantly tending too much to the brain.