An excerpt from and article by DZOGCHEN PONLOP RINPOCHE| MAY, 2006
“The Buddha offered a progression of teachings appropriate to people’s different spiritual needs. With great compassion and incomparable skill, the enlightened master Buddha Shakyamuni taught in any way that would lead beings on a correct path to liberation and, finally, to buddhahood. Sometimes the Buddha taught in a way that led his disciples gradually to an understanding of the absolute nature of reality, and in these situations, he taught about relative reality first. At other times he taught the ultimate nature directly and explicitly.
“Over the course of his forty-five years of teaching, the Buddha turned the wheel of dharma three times, initiating new cycles of teachings for the benefit of sentient beings. These three turnings are commonly known as the dharmachakra (“dharma wheel”) of the four noble truths, the dharmachakra of essencelessness or non-characteristics—emptiness, and the dharmachakra of full or thorough distinction—buddhanature.
“The first turning of the wheel of dharma took place in Deer Park at Sarnath, not long after the Buddha’s enlightenment. At this time, Buddha presented teachings on the four noble truths, karma, and the selflessness of the person. These teachings form the basis for what is called the “common vehicle,” also known as the path of individual liberation, or the vehicle of the “listeners” or “hearers.””
“The second and third turnings form the basis of the vehicle known as the Mahayana. The second turning took place at Rajagriha on Vulture Peak Mountain. There the Buddha taught the Prajnaparamita Sutras, or the Sutras of Transcendent Knowledge. In this phase of his teaching, Buddha emphasized the emptiness or lack of true existence of both self and phenomena. The third turning took place in various cities, beginning in Vaishali. At this time, Buddha presented the teachings on tathagatagarbha, or buddhanature. These focus on the luminous nature of emptiness and reveal that the potential for buddhahood has always been present within our hearts. At the same time, in the final turning of the wheel of dharma, Buddha clearly distinguished between the indicative and definitive meanings of his various teachings.”