Ever since the Buddha's lifetime, people have been trying to express the ultimate meaning of Buddhism in a form that makes complete rational sense. The Prajnaparamita or "Perfection of Wisdom" teachings offer a giddying counterbalance to this exercise, and a sophisticated slap in the face to anyone undertaking it. Emerging 2000 years ago as the core-teachings of Mahayana Buddhism, texts such as the Ratnaguna-samcayagatha, the Diamond Sutra and the Heart Sutra were to give new impetus to the ideal of the Bodhisattva, one whose entire energies are dedicated to the attainment of enlightenment for the sake of all beings. They are unique, extraordinary teachings, addressing the practical, everyday concerns of Buddhists, but in a way that can leave the rational mind spinning. Sangharakshita has a rare combination of scholarship, intellectual clarity and insight. As founder of the Western Buddhist Order he is necessarily alive to the immediate concerns of Buddhists practising in the West. This perspective is crucial in a guide to texts that seem to express the goal and justification for Buddhist practice in a "breath of nonsense, a touch of Lewis Carroll".