None of these things which casually influence the mind deserve to be called passions: the mind, if I may so express it, rather suffers passions to act upon itself than forms them. A passion, therefore, consists not in being affected by the sights which are presented to us, but in giving way to our feelings and following up these chance promptings: for whoever imagines that paleness, bursting into tears, lustful feelings, deep sighs, sudden flashes of the eyes, and so forth, are signs of passion and betray the state of the mind, is mistaken, and does not understand that these are merely impulses of the body. Consequently, the bravest of men often turns pale while he is putting on his armour; when the signal for battle is given, the knees of the boldest soldier shake for a moment; the heart even of a great general leaps into his mouth just before the lines clash together, and the hands and feet even of the most eloquent orator grow stiff and cold while he is preparing to begin his speech.