The effect of a too close application of mind to study on the bodily health has long been a matter of common observation. The Roman orator, Cicero, points out forcibly the dangers arising from inordinate exertion of mind; and he has laid down some rules for guarding against the effects of study. M. Van Swieten, in alluding to this subject, relates the case of a man whose health was severely injured, by what he calls "literary watchings." Whenever he listened with any attention to any story, or trifling tale, he was seized with giddiness; he was in violent agonies whenever he wanted to recollect any thing which had slipped his memory; he oftentimes fainted away gradually, and experienced a disagreeable sensation of lassitude. Rousseau has very justly remarked, that excessive application of mind "makes men tender, weakens their constitutions, and when once the body has lost its powers, those of the soul are not easily preserved. Application wears out the machine, exhausts the spirits, destroys the strength, enervates the mind, makes us pusillanimous, unable either to bear fatigue, or to keep our passions under."[3] Shakspeare appears to have formed a just conception of the great injury which the corporeal frame experiences from a too close application of mind. The immortal bard observes,-- "----Universal plodding poisons up The nimble spirits in the arteries As motion and long-during action tires The sinewy vigour of the traveller." _Love's Labour Lost._ In the consultations of Wesper we find related the history of a young man of family 22 years of age, who, having applied himself incessantly to intense mental exertion, was seized with a fit of insanity, in which fit he wounded several persons and killed his keeper. Catalepsy has been known to have been produced by great mental application. Fomelius gives us a remarkable instance of it. A man (says he) who passed whole nights in writing and studying, was suddenly attacked with a fit of catalepsy: all his limbs stiffened in the attitude he was in when the disease first seized him. He remained upon his seat, holding the pen in his hand, and with his eyes fixed on his paper, so that he was considered to be still at his studies, till being called to, and then shaken, he was found to be without motion or sensation.[4] Many extraordinary instances are on record, of remarkable changes having been produced in birds by an affection of the animal passions. The following fact is related by Mr. Young, in the Edinburgh Geographical Journal. A blackbird had been frightened in her cage by a cat; when it was relieved, it was found lying on its back, quite wet with perspiration. The feathers fell off, and were renewed, but the new ones were perfectly white.