Find out each person's thumbscrew. This is the art of setting their wills in action. It needs more skill than resolution. You must know where to get at anyone. Every volition has a special motive that varies according to taste. All people idolize something; for some it is fame, for others self-interest, for most it is pleasure. Skill consists in knowing these idols in order to bring them into play. know a person's mainspring of motive and you have as it were the key to his will. Have resort to primary motives, which are not always the highest but more often the lowest part of his nature because there are more dispositions badly organized than well. First guess a person's ruling passion, appeal to it with words, set it in motion by temptation, and you will always checkmate is freedom of will.

THE ART OF WORLDLY WISDOM BY BALTHASAR GRACIAN
TRANSLATED BY JOSEPH JACOBS 1892