The morality found in all the precepts can be summarized in three simple principles:
'To avoid evil; to do good, to purify the mind.' This is the advice given by all the Buddhas. --(Dhammapada, 183)
In Buddhism, the distinction between what is good and what is bad is very simple: all actions that have their roots in greed, hatred, and delusion that spring from selfishness foster the harmful delusion of selfhood. These action are demeritorious or unskillful or bad. They are called Akusala Kamma. All those actions which are rooted in the virtues of generosity, love and wisdom, are meritorious -- Kusala Kamma. The criteria of good and bad apply whether the actions are of thought, word or deed.
- Venerable K. Sri Dhammananda Maha Thera, "What Buddhists Believe"