
This illustration is located on the back (west) wall within the main chamber. It is based on the contents of the Mahayana Brahmajala Sutra. It explains the 10 major and 48 minor precepts of a Bodhisattva.
The mural has a symmetrical layout and encompasses the whole of the back wall. Vairocana Buddha, in the center, expounds the Bodhisattva precepts. Bodhisattvas, disciples and heavenly beings surround the Buddha. Monks make vows and uphold the precepts, as seen on either side of the upper register. Along the bottom left is a gathering of numerous beings, including Sakra, Brahma, Surya, Candra, the young, the old, the impoverished, and various wild and domesticated animals. They traverse across the landscape toward the Buddha in the center to listen to the Dharma.
A monk, located in the middle register of the right section, sits on a bed with one hand raised, holding an ax. He appears to be in the process of chopping his own knee, and blood gushes out of a wound, while a benefactor kneels before him, holding a plate. The words of the cartouche are no longer legible. This image is part of a sequence of illustrations which run from left to right in this section of the mural. They are thought to illustrate the punishments for those who break the ten major precepts. This particular detail likely refers to the sixth precept, which forbids precept holders from broadcasting the faults of the sangha.
For more details, go to the Encyclopedia of Buddhist Arts: Caves T-Z, page 1623.