Emotion, according to scientific writers of the Renaissance, is a physiological as well as a psychological phenomenon. A passion provokes muscular activity in the heart and movements of humors to or from the heart. It is accompanied, moreover, by intensification of two of the four primary physical qualities: heat, cold, moisture, and dryness. Heat and dryness, for instance, are concomitants of anger; an angry man is a hot, dry man. A sorrowful or fearful man is a cold, dry man. A desirous, hopeful, or joyful man is a hot, moist man. Since choler is a hot, dry humor, men of choleric complexion, or temperament, are physically predisposed to anger, and anger is the passion most characteristic of them. Since melancholy is a cold, dry humor, melancholy men are naturally prone to fear and sorrow. Since blood is hot and moist, sanguine persons are naturally inclined to desire, hope, and joy. Phlegmatic men are relatively passionless, for phlegm is cold and moist and there are no cold and moist passions.