Bright dilated eyes are among the phenomena of detumescence, and are very frequently noted in persons of a pronounced erotic temperament. This is, indeed, an ancient observation, and Burton says of people with a black, lively, and sparkling eye, "without question they are most amorous," drawing his illustrations mostly from classic literature.[154] Tardieu described the erotic woman as having bright eyes, and Heywood Smith states that the eyes of lascivious women resemble, though in a less degree, those of the insane.[155] Sexual excitement is one among many causes--intellectual excitement, pain, a loud noise, even any sensory irritation--which produce dilatation of the pupils and enlargement of the palpebral fissure, with some protrusion of the eyeball. The influence of the sexual system upon the eye appears to be far less potent in men than in women.[156] Sexual desire is, however, by no means the only irritant within the sexual sphere which may thus influence the eye; morbid irritations may produce the same effect. Milner Fothergill, in his book on _Indigestion_, vividly describes the appearance of the eyes sometimes seen in ovarian disorder: "The glittering flash which glances out from some female irides is the external indication of ovarian irritation, and 'the ovarian gleam' has features quite its own. The most marked instance which ever came under my notice was due to irritation in the ovaries, which had been forced down in front of the uterus and been fixed there by adhesions. Here there was little sexual proclivity, but the eyes were very remarkable. They flashed and glittered unceasingly, and at times perfect lightning bolts shot from them. Usually there is a bright glittering sheen in them which contrasts with the dead look in the irides of sexual excess or profuse uterine discharges." The activity of the glandular secretions, and especially those of the skin, during detumescence, would lead us to expect that such secretory activity is an index to an aptitude for detumescence. As a matter of fact it is occasionally, though not frequently, noted by medical observers. It is stated that the erotic temperament is characterized by a special odor.[157] The activity of the sweat-glands is seldom referred to by medical observers in describing persons of erotic temperament, although the descriptions of novelists not infrequently contain allusions to this point, and the literature of an earlier age shows that the tendency to perspiration, especially the moist hand, was regarded as a sure sign of a sensual temperament. "The moist-handed Madonna Imperia, a most rare and divine creature," remarks Lazarillo in Middleton's comedy _Blurt, Master-Constable_, to quote one of many allusions to this point in the Elizabethan drama.