It is, however, only at a later period when the Aryan conquest had moved out of the Punjab to the South and West, and just on the eve of the formation of the _Rigveda_ as a collection of religious hymns, that we find the beginnings of philosophic speculation.[4] A few hymns, chiefly in the tenth Mondol, ask questions about the origin of the universe, and venture some naive guesses on that tremendous subject. Some of the hymns[5] take for granted the existence of primeval matter, and ask how or by whom it was transformed into a _cosmos_. In others[6] there is more monotheistic feeling, and a Creator, either Hiranyagarbha or Visvakarman, is described. In others[7] the strain of thought is agnostic. B. With the collection of the hymns of the _Rigveda_ we pass into a new and very different period, the literature of which is altogether priestly. To this age belong the two great sacerdotal manuals, the _Sāmaveda_[8] or Chant-book, and the _Yajurveda_[9] or Sacrifice-book, and those extraordinary collections of priestly learning, mythology and mysticism, the Brāhmanas.[10] These books introduce us to changed times and changed men, to new places and a new range of ideas. The fresh poetry of the youth of India has given place to the most prosaic and uninteresting disquisitions in the whole world.[11] The home of this literature is the great holy land of Brahman culture, stretching from the Sutlej on the West to the junction of the Jumna and the Ganges at Prayāga.[12] In this period the doctrine of the transmigration of the soul first appears.[13] C. The Aranyakas[14] and Upanishads[15] place before us a further development of Indian religion. Reflection led to the perception of the great truth, that the kernel of religion is not the ritual act but the heart of piety behind it. Many a man who had found the endless formulæ and the showy ceremonial of the sacrifice a serious hindrance to real religion, sought refuge from the noise and distraction of the popular cult in the lonely silence of forest or desert. To run over the sacrifice in one’s own mind, they reasoned, was as acceptable to the gods as to kill the horse or to pour the ghee upon the altar fire. But they soon reached the further position, that for the man who has attained TRUE KNOWLEDGE sacrifice is altogether unnecessary. For knowledge of the world-soul emancipates a man from the chain of births and deaths and leads to true felicity. The main purpose, thus, of the Upanishads, is to expound the nature of the world-soul. Their teaching is by no means uniform. Not only do the separate treatises differ the one from the other; contradictory ideas are frequently to be met with in the same book. They all tend to idealistic monism; they all agree in identifying the soul of man with the world-soul; but on the questions, whether the latter is personal or impersonal, how spirit and matter are related, and how the human soul will join the divine soul after death, there is no unanimity.[16]