This is the fourth of a six week class series on the Precepts, the moral and ethical guidelines that shape our zen practice. These are not deemed to be "commandments"; rather they can be used as koans and questions with which to examine our life and behavior, helping to guide us towards skillful action and the cultivation of compassion.   This week Shintai will lead a discussion on Precepts 4-6 of the Ten Grave Precepts:  Do not speak dishonestly", "Do not become intoxicated" and "Do not dwell on past mistakes."