Metta (loving kindness) practice leads us into the exploration of all of the heart's responses to life. Especially good grounds for understanding are in the experience of loving kindness, its near enemy of affection with attachment, and its far enemy of ill will.
Sylvia Boorstein and Donald Rothberg explore in dialogue lovingkindness and its relationships with muddita (appreciative joy), gratitude, and equanimity. Mature lovingkindness integrates all of these qualities.