According to legend, on the 22nd day of the ninth month of the Tibetan calendar, the Buddha descends to the human realm, and stays in freshly painted homes. Every year, in the three weeks leading up to "Buddha's Descent Day," hundreds of locals and volunteers from near and far show up at the Potala Palace, bowls and lime paint in hand, to honor a tradition that dates back to the 17th century, giving the palace's outer walls a fresh coat to welcome his return.