The Prajnaparamita ("perfection of wisdom") sutras are one of the great legacies of Mahayana Buddhism, giving eloquent expression to some of that school's central concerns: the perception of shunyata, the essential emptiness of all phenomena; and the ideal of the bodhisattva, one who postpones his or her own enlightenment in order to work for the salvation of all beings.            The Prajnaparamita literature consists of a number of texts composed in Buddhist India between 100 BCE and 100 CE. Originally written in Sanskrit, but surviving today mostly in their Chinese versions, the texts are concerned with the experience of profound insight that cannot be conveyed by concepts or in intellectual terms. The material remains important today in Mahayana Buddhism and Zen.            Key selections from the Prajnaparamita literature are presented here, along with Thomas Cleary's illuminating commentary, as a means of demonstrating the intrinsic limitations of discursive thought, and of pointing to the profound wisdom that lies beyond it.            Included selections from:    *  The Scripture on Perfect Insight Awakening to Essence    *  The Essentials of the Great Scripture on Perfect Insight    *  Treatise on the Great Scripture on Perfect Insight    *  The Scripture on Perfect Insight for Benevolent Rulers    *  Key Teachings on the Great Scripture of Perfect Insight    *  The Questions of Suvikrantavikramin