 From a historical standpoint, Śaṅkara’s textual works define his identity. He composed our earliest complete extant commentaries on the Brahmasūtras, Bhagavadgītā, and the ten principal Upaniṣads consisting of the Īṣā, Kena, Kaṭha, Praṣna, Muṇḍaka, Māṇḍūkya, Aitareya, Taittirīya, Chāndogya, and Bṛhadāraṇyaka Upanisads. Śaṅkara’s commentary on the Māṇḍukya is part of his extensive commentary on the Gauḍapādakārikās’ explanation of the Māṇḍūkya. Śaṅkara also composed an independent work titled the Upadeśasāhasrī (A Thousand Teachings). There are hundreds of other texts attributed to Śaṅkara, but their authorship is questionable and most were likely composed in later centuries by monastic heads who held a “Śaṅkarācārya” title. (See Potter 1981: 115–117; Hacker 1995; and Mayeda 1965a, 1965b, and 1967 for discussions of Śaṅkara’s likely works, as well as Hacker’s criteria for determining their authenticity. See Sundaresan 2002 for some critiques and expansion of Hacker’s criteria).