We begin this Inquiring Mind issue on the different schools of Buddhism with the following description of the Three Vehicles, excerpted from Wisdom and Compassion: The Sacred Art of Tibet by Marylin Rhie and Robert Thurman.
The Three Vehicles are a way of classifying Buddhist teachings. The first, Theravada, is the monastic vehicle of early Buddhism, centered on the Four Noble Truths and the freedom and enlightenment of the individual.
The second, Mahayana, is the messianic social vehicle, centered on emptiness and great compassion, and freedom and enlightenment for all beings.
The third, Vajrayana, is the esoteric, tantric vehicle, centered on the implementation of compassion as great bliss, the use of artistic imagination to reconstruct the self and the universe, and the acceleration of all beings toward freedom and enlightenment.