The Buddha Śākyamuni gave teachings on three different levels, referred to as the three turnings of the Dharma wheel. On the first occasion at Sarnath, he expounded the doctrine of the four noble truths. Later, at Vulture Peak, he set forth the doctrine of emptiness subsequently recorded in the Prajñāpāramitā sutras. Finally, on various occasions, he gave teachings on the tathāgatagarbha, the buddha nature, such as are recorded in the Sandhinirmochana and other sutras. [TPQ 2010]