There are two kinds of inner peace. The first is somewhat like that which the ancient Stoics cultivated: the result of controlling emotions and disciplining thoughts, the result of will and effort applied to the mastery of self. It brings with it, at best, a contentment with what one has, at least, a resignation to one's lot. The second is much deeper, for it comes out of the Overself. It is the blessed result of Divine Grace liberating one from the craving for existence.
-- Notebooks Category 6: Emotions and Ethics > Chapter 3: Discipline Emotions > # 30