The concept of the mahant- ātman-, or “vast self”, found in some of the Early and Middle Upaniṣads, has, at least since the days of Hermann Oldenberg, been explored by a number of scholars, most notably by van Buitenen :103–114, 1964). These studies have usually emphasized the cosmic implications of this concept; the vast ātman- being the non-individualized spirit that brings forth and pervades the universe, then enters the bodies of all created beings as their animating principle. As such it (...) precedes the mahān, or mahat, of the Sāṃkhya philosophy. The present paper argues that the concept of a mahant- puruṣa- or “vast person”, appearing parallel to the vast ātman in these texts, is in fact older, being traceable to Middle Vedic texts; the emergence of the Upaniṣadic ātman doctrine has eventually led to its replacement by the mahān ātmā. Originally, it is argued, the adjective mahant- stressed the difference between this “vast” puruṣa, who is said to dwell in the sun, and the minute puruṣa within man, who is seen as the tiny “person” in one’s pupil, or resides in the heart, having the size of a thumb. In contradistinction to the ātman, the puruṣa is a thoroughly anthropomorphic soul-concept, a “person” within the person. The ultimate identity between this tiny soul-person and the puruṣa in the sun is a recurring, but little studied, motif in the micro-macrocosmic speculations of the Brāhmaṇa texts. This “vast”, solar puruṣa is sometimes identified with the Puruṣa or primeval man of Ṛgveda 10.90, from whose body the universe was formed, and much of the imagery surrounding the vast puruṣa of Middle and Late Vedic literature seems to derive from this hymn. (shrink)