Tri-kāṇḍī ("Three books") is a Sanskrit-language work on the philosophy of language and grammar (vyakarana), written by the 5th-century grammarian Bhartṛ-hari in present-day India. Some 19th-20th century printed editions refer to it by the title Vākya-padiya, which is actually the title of a part of it.
Trikāṇḍī comprises three books (kāṇḍas):
Agama-samuchchaya ("Collection of traditionally received knowledge") or Brahma-kāṇḍa
Vākya-padiya or Vākya-kāṇḍa
Prakirna(ka) ("Miscellany") or Pada-kāṇḍa
The alternative titles - Brahma-kāṇḍa, Vakyā-kāṇḍa, and Pada-kāṇḍa - likely do not originate from the author.
The early printed editions of the work, such as those from 1888 and 1905, incorrectly presented Vākya-padiya as the title of the entire collection containing three books. Vākya-padiya originally referred only to the second book of the collection, and later came to refer to the first two books. The term "Vākya-padiya" likely referred to the first two books by time of Vṛṣabha (c. 650), and definitely in the time of Hela-raja (c. 980) and Vardhamana (the author of Gana-ratna-mahodadhi, c. 1140).
The first two parts are divided into kārikās (verses) and vṛtti (commentary). Since the earliest times, tradition attributes the authorship of the vṛttis to Bhartṛ-hari himself, although some manuscripts name Hari-vṛṣabha alias Vṛṣabha as their author.
Scholar Ashok Aklujkar theorizes that Bhartṛ-hari originally conceived the three books as "relatively independent" treatises, but later thought of unifying them into a single work. However, he died after composing commentaries (vṛtti) on the first two books. Dharma-pala (6th century) wrote the vṛtti on the third book.
The Book I discusses the concept of Brahman, stating that it "creates the diversity of the world out of language". It briefly discusses the Vedic branches and the Vedas as a source of rites, smṛti, schools of philosophy, and traditional knowledge. The author highlights the importance of the grammar (vyakarana), calling it "the door to liberation", and describing it as the first among the six auxiliary sciences, because other sciences can be understood only through it.