The relation of Buddhism and the Upanishads!
According to Oldenberg, the Upanishads paved the way for Buddhism. The principle of Karma in the Upanishads became the source of inspiration for almost the entire doctrine of momentariness, and many other doctrines of Buddhism had their origin in the Upanisads.
As Rhys Davids points out, “Gautama was born and brought up and lived and died a Hindu.”
The following facts also establish the intimate relation of Buddhism with the Upanishads:
Buddhist ritualism has its source in Chandogya Upanishad where it is said that in the beginning there was only as at and later on Sat came out of it. Samskara has also endorsed this fact.
(ii) Theory of No-soul:
The theory of no-soul as found in Buddhism has its source in the Upanishads. Its origin can be treated to the Katbopanisad, where it has been said that when a man dies, different persons think differently about his soul. Some say that it has still some existence; others say that its existence has ended.
(iii) Pessimism and Momentarism:
The roots of the pessimism and momentarism of Buddhism can be traced to the Upanisadic philosopher Nachiketa who says that, “All is misery”, and, “All is momentary”.
(iv) System of Monasteries:
The Buddhist system of monasteries can be traced to Braiaranyaka Upanishad, where it has been said that the man who is apathetic to the world should transcend the carvings for wealth and progeny, etc., and lead the life of a hermit.
The metaphysics and episteinology of the Vijanavada can be traced to the Aitereya Upanishad, where it has been said that everything in this world has its origin in consciousness.
The Buddhist idea of re-birth has its roots in Kathopanisad where it has been said that the souls assume new bodies according to their actions and knowledge.”