The Zen term for the evening meal—yakuseki—literally means “medicine stone.” Originally Buddhist monks in india ate only once a day, and the meal was required to be finished before noon. This rule was enforced with surprising strictness: past noon, monks were forbidden even to swallow bits of food stuck between their teeth or oil left on their tongue or lips. Eventually, in Chinese Chan monasteries the number of meals per day was increased to two, one in the morning and one at noon. In the evening it was the practice to place a heated stone on the belly to soothe pangs of hunger. This stone was called the “medicine stone.” Only the name survived to later ages, eventually becoming the accepted term for the evening meal.
In a Zen monastery the evening meal is not a formal meal, and so does not involve the sacred Buddha bowl.