If we are not stained by the three poisons [craving, aversion, and ignorance], we will gradually acquire the altruistic attitude of wishing to benefit others. . . . The source of all virtue and nonvirtue is thus the mind alone, and it is over our minds that we must mount an unceasing guard. . . . Subduing the mind leads naturally to the development of a good heart.

Dudjom Rinpoche, Counsels From My Heart