The word "mu" is one ancient Zen teacher's response to the earnest question of whether even a dog has "buddha nature". 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, "sitting with Mu" is an apt description for all Zen meditation, and it is said that all the thousands and thousands of koans in the Zen tradition are...