When persons experience pleasant feelings, they delight, relish, and indulge in them. The tendency toward attachment naturally accumulates for such persons.
When persons experience unpleasant feelings, they sorrow, worry, lament, despair, and are deluded. The tendency toward aversion naturally accumulates for such persons.
When persons experience feelings neither pleasant nor unpleasant, they do not understand in accordance with reality the causes for these feelings, the cessation of these feelings, the delicious charm of these feelings, the penalty from these feelings, and the skillful means of escape from these feelings. The tendency toward indifference naturally accumulates for such persons. —Buddha Shakyamuni