Shankara commented on Krishna, on the Upanishads, on the Brahma Sutras. Ramanuja commented on the ancient enlightened people, Vallabha did the same. It has always been so in the East, because much dust gathers as time passes. Now, the Upanishads were written in a totally different world. That man has disappeared, that mind has disappeared, that world no more exists.
Source: Philosophia Perennis: The Perfume of Absolute Contentment (S. 122/123)
Contributed by: hans-wolfgang