With a combination of playfulness and humility, Sensei Noah Kodo Roen presents Case 21 of Book of Serenity, “Yunyan Sweeps the Ground,” and explores the dichotomy of mindfulness and busyness, as well as the connections of Yunyan and Daowu to stories in other koans, and Yunyan’s place as an ancestor in the soto lineage. Kodo explores the sweeper, the broom, the brother, and the moon, and the possibility that this case holds for all of us in our times.