Philosophical Development from Upanishadic Metaphysics to Scientific Realism Upanishadic philosophy: preparing the ground for rationalism Although the Upanishadic texts (like some of the earlier Vedic texts) are primarily concerned with acquiring knowledge of the "soul", "spirit" and "god" - there are aspects of Vedic and Upanishadic literature that also point to an intuitive understanding of nature and natural processes. In addition, many of the ideas are presented in a philosophical and exploratory manner - rather than as strict definitions of inviolable truth. Although the Upanishadic texts goaded the Upanishadic student to concentrate on comprehending the inner spirit, rational investigation of the world by other scholars was not entirely squelched, and eventually, the Upanishadic period gave way to an era which was not inimical to the development of rational ideas, even encouraging scientific observation and advanced study in the fields of logic, mathematics and the physical sciences. Following an era when rituals and superstitions had begun to proliferate, in some ways the Upanishadic texts helped to clear the ground for greater rationalism in society.
Brahmin orthodoxy and ideas of ritual purity were superseded by a spiritual perspective that eschewed sectarianism and could be practised universally, unfettered by an individual's social standing. Much of the emphasis was on discovering "spiritual truths" for oneself as opposed to mechanically accepting the testimony of established religious leaders. Although there is a thematic commonality to the Upanishadic discourses, different commentators offered subtly varying perspectives and insights. The concept of god in Upanishadic (and even earlier Vedic) thinking was quite different from the more common definition of god as creator and dispenser of reward and punishment. The Upanishadic concept of god was more abstract and philosophical. Different texts postulated the doctrine of a universal soul that embraced all physical beings. All life emanated from this universal soul...