Shī- Hù started his translations after the rising of Esoteric Buddhism (Mizong). The sutras translated by Shī- Hù can be viewed as the conclusion of prajñāpāramitā sūtraṃ. Shī- Hù translated five outline-sutras, of which each contains less than 2300 Chinese characters. Though outline-sutras are small, the essence of prajñāpāramitā is contained within. Dì-Shì-Sutra contains three parts to expose the meaning of prajñā-pāramitā. Liǎo-Yì-Sutra, with the minimal size, exposes the methods for practiciing prajñā-pāramitā. Wǔ-Shí-Sutra lists 52 terms which are related to the practicing of prajñā-pāramitā. Wǔ-Shí-Sutra can be viewed as a further abstraction of Liǎo-Yì-Sutra. Bǎi-bā-Sutra contains 108 terms related to prajñā-pāramitā, which can be divided into 7 groups for understanding the prajñā-pāramitā. Originally, Heart-Sutra was takes as a mantra sutra. Shī-Hù avoided using the word ＂heart＂ and, instead, using Fomu (Buddha-mother). The reason for this is explored in a great depth. Five paragraphs from Middle Prajñā Sutra are discussed to show that prajñā-pāramitā is dharani or Siddhaṃ letter 'à'. It proves that Heart-Sutra is the core of Prajñā Sutras based on practicing the ＂sound＂. A comparison among three different translations, respectively translated by Xuán-Zàng, Shī-Hù, and Tán-Xī-Yǒng, is made on a sentence-by-sentence base.
