For the loss that cannot be undone. Patacara, Kisa Gotami, the mustard seed.
Daughter of a Savatthi merchant who eloped with a servant, lost her husband, her two children, and her parents in successive days, and wandered mad through the streets of Savatthi until the Buddha said four words to her: "Sister, recover your senses." She became one of the chief bhikkhunis, foremost in mastery of the Vinaya.
Three characteristics belong to all conditioned phenomena: impermanence, unsatisfactoriness, and non-self. To see them clearly in one's own experience is the precondition of liberating insight.
The cultivation of unconditional good-will toward all beings. The first of the four brahmaviharas, the 'divine abidings' — and the antidote the Buddha gave to a forest of monks who could not stay in their forest.