There is thus no speculative system to be drawn from these books. Those of their ideas that are held with settled, serious conviction, are taught rather dogmatically than philosophically; and, on the other hand, where there is freedom of thought, there is rather a groping after the truth than any definite train of illuminative reasoning. Yet this occasional, conversational, unconventional character gives these simple and sincere treatises their greatest charm, and fits them for that devotional use to which so many generations of pious readers have put them. To this early period there belong only the first great group of prose Upanishads, the _Brihadāranyaka_, _Chāndogya_, _Taittirīya_, _Aitareya_, _Kaushītaki_ and parts of the _Kena_.[17] D. In bold contrast to this unsystematic meditation on the Eternal Spirit there stands out the severe, clear-cut, scientific system of Kapila,[18] the first Indian thinker who dared to trust the unaided human mind. Buddhist tradition recognizes that he preceded Buddha, and connects him with Kapila-vastu, the birth-place of Buddha, the site of which was discovered as recently as December 1896.[19] He drew a sharp distinction between matter and spirit and declared both to be eternal, without beginning and without end. The material universe develops in accordance with certain laws out of primeval matter, _prakriti_. Spirit, on the other hand, exists as an indefinite number of individual souls, each eternal. There is no supreme divine spirit. The value of this system lies chiefly in its severely logical method, which demands that all reasoning shall proceed from the known elements of experience. It has exercised a very great influence on Indian thought, partly by its method, but still more perhaps through its cardinal ideas, the eternity of matter, the eternity of individual souls, the three _gunas_, the great cosmic periods, and _kaivalya_, _i. e._, the attainment of salvation through the separation of the soul from matter. This great system is known by the name Sānkhya, _i. e._, enumeration, seemingly on account of the numbering of the twenty-five _tattvas_, or principles, which it sets forth.[20] Such is the _Sānkhya_ system; but it would be dangerous to affirm that the whole came from Kapila; for no treatise written by him has come down. The earliest systematic manual of the philosophy extant to-day is the _Sānkhya-Kārikā_ of Isvara-Krishna, which dates from the early Christian centuries.[21] E. Shortly after the Sānkhya system, and in close dependence upon it, there appeared Buddhism and Jainism; but as these great religions exercised no very definite influence on the main stream of Indian thought for several centuries, we shall not linger over them.