This book contains two of the most important and popular Sutras in the Buddhist world, summarizing the wealth and wisdom of the most fertile period of evolution of the Great Vehicle. They constitute only a small part of the voluminous collection of texts of secret wisdom, the "Prajna Paramita" (i.e., the "Perfect or Transcendent Wisdom"), which describes the perfect nature of things and the ways in which it is perceived and expressed by the human spirit. These texts are considered among the oldest and most fundamental of the Mahayana.