The Prajñāpāramitā-hṛdaya sūtra is a religious document of the first importance. It carried Hiuen-tsiang through the Gobi desert, was reproduced, in writing, on stones, in recitation throughout Asia from Kabul to Nara, and formed one of the main inspirations of the Zen school, occupying in Buddhist mysticism about the same place the “Mystical Theology” of Pseudo-Dionysius Areopagita occupied in Christian. Unlike other very short Prajñāpāramitā-sūtras, the Hṛdaya is of great philosophical interest. The Svalpākṣara, and other abbreviations, were designed to bring the benefits of Prajñāpāramitā within the reach of those unable either to study or understand it. The Hṛdaya alone can be said to have gone really to the heart of the doctrine. The historical analysis of its sources can contribute to the understanding of this sūtra, by restoring its component parts to their context in the larger Prajñāpāramitā sūtras.