Melissa Myozen Blacker ’76 is co-editor (with James Ishmael Ford) of The Book of MU: Essential Writings on Zen’s Most Important Koan (Wisdom Publications, 2011). The word “mu” is one ancient Zen teacher’s response to the earnest question of whether even a dog has “buddha nature”—and discovering for ourselves the meaning of the master’s response is the urgent work of each of us who yearns to be free and at peace. “Practicing Mu” is synonymous with practicing Zen, and “sitting with Mu” is an apt description for all Zen meditation. It has been said that thousands and thousands of koans…