The Heart of Perfect Wisdom Sutra or Heart Sutra or Essence of Wisdom Sutra (Sanskrit: प्रज्ञापारमिताहृदय Prajñāpāramitā Hṛdaya) (the word sutra is not present in known Sanskrit manuscripts) is a well-known Mahāyāna Buddhist sutra that is very popular among Mahayana Buddhists both for its brevity and depth of meaning. Buddhist writer and translator Bill Porter calls the Heart Sutra the best known and most popular of all Buddhist scriptures.