In striving to understand tonglen and other dharma practices, I think about a simile that my father used to use when teaching forgiveness or compassion. He would say that each one of our unskillful reactions to life—usually some form of clinging or aversion—is like a thin sheet of rice paper that we lay over our heart. Think about how many sheets of fear, of anger, of resentment, of judgment we lay over our heart each day! We do it constantly, until eventually our heart is buried beneath such a thick wall of paper that it becomes bulletproof. Each piece of paper in itself is not a problem; it’s just rice paper—it dissolves in water, or we can break through it with the flick of a finger. But when our habitual reactive tendencies of clinging and aversion go unchecked, the paper becomes thicker and thicker until   it becomes like armor.

All of the Brahma Vihara practices and tonglen have the ability to initiate the process of dissolving the armoring of the heart. Each time we repeat our metta phrases or breathe out compassion in tonglen, we are dissolving the rice paper; we’re getting closer and closer to our true heart’s natural compassion.