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. Emerging 2000 years ago as the core-teachings of Mahayana Buddhism, texts such as the Ratnaguna-samcayagatha, the Diamond Sutra and the Heart Sutra gave new impetus to the ideal of the Bodhisattva, one whose energies are dedicated to the attainment of enlightenment for the sake of all beings.