The Vedic seers did not climb the Supermind, they glimpsed the Supermind from the plane of intuition and few perhaps rose to the Overmind. Had they actually entered the Supermind there would have been some hints about the various transformations. There is mention about illumination in the mind but nothing more.
The Vedic seers do speak of the consciousness of immortality which is a very different thing than physical immortality. Realisation of the soul, of the universal Self, even of the Infinite in the finite is realisable but physical immortality implies transformation of the natural instruments, organs and cells. This has never been attempted.
In the words of Sri Aurobindo,
‘The quarrels of religious sects are like the disputing of pots, which shall be alone allowed to hold the immortalizing nectar. Let them dispute, but the thing for us is to get at the nectar in whatever pot and attain immortality.
What is this nectar of immortality? This consciousness of immortality… is OUR becoming conscious of the realms where immortality exists; but to bring immortality into the physical consciousness requires not only a transformation of physical consciousness but a transformation of physical substance as well. So….’
Even so the Aim of the Vedic Rishis was primarily the consciousness of immortality. It is in search of this that they climbed up the ladder of consciousness. The Aim of Sri Aurobindo’s Yoga, His quest, so to say, was Perfection, not simply the state of inner Perfection that one can realise through the Yoga of the Gita but Perfection in the most outward movements and activities of nature, and through it, a growing terrestrial Perfection.
There are other differences as well but that can be for later on. But just to mention one of them, the path of the Rishis is primarily through meditation and worship. Sri Aurobindo’s Integral Yoga includes works and bhakti, not only as auxiliaries but as central elements in the sadhana. It also bypasses the gods and rituals that plays an important part in the yoga of the Vedic seers.
