If a man regrets his own conduct, be it a single action or a whole course of actions, he will feel some self-contempt and get depressed. This is a valuable moment, this turning of the ego against itself. If he takes advantage of it to ferret out the cause in his own character, in his own person as it got built up through its reincarnations, he may remold it in a more satisfactory way. This inner work is accomplished by a series of creative and positive meditations.
-- Notebooks Category 6: Emotions and Ethics > Chapter 1: Uplift Character > # 273