I MUST now advert in a general way to the six systems of philosophy which grew out of the Upanishads. They are sometimes called the six Śāstras or bodies of teaching, sometimes the Shaḍ Darśanas or six Demonstrations. They are—

1. The Nyāya, founded by Gotama.

2. The Vaiśeshika, by Kanāda.

3. The Sānkhya, by Kapila.

4. The Yoga, by Pataṅjali.

5. The Mīmāṉsā, by Jaimini.

6. The Vedānta, by Bādarāyaṇa or Vyāsa.

They are delivered in Sūtras or aphorisms, which are held to be the basis of all subsequent teaching under each head.

It is as impossible however to settle the date of any of them with certainty as it is to determine the period of the composition of any single work in Sanskṛit literature. Moreover, it is scarcely practicable to decide as to which of the six systems of philosophy preceded the other in point of time. All we can say is, that about 500 years before the commencement of the Christian era a great stir seems to have taken place in Indo-Āryan, as in Grecian minds, and indeed in thinking minds everywhere throughout the then civilized world. Thus when Buddha arose in India, Greece had her thinker in Pythagoras, Persia in Zoroaster, and China in Confucius. Men began to ask themselves earnestly such questions as—What am I? whence have I come? whither am I going? How can I explain my consciousness of personal existence? What is the relationship between my material and immaterial nature? What is this world in which I find myself? Did a wise, good, and all-powerful Being create it out of nothing?