I don’t think there is any, nor anywhere in the ancient revelations, not even in his earlier writings. The planes and parts of the being described in the Letters on Yoga pertaining to the 1930s do not elucidate anything of the kind anywhere. There was neither a mention of it in the course of conversations after the accident in November 1938. It means, it started taking definite shape only after that: its emergence is the event of the 1940s, perhaps of the mid 40s. It is directly related with the yogic possibility of the universal descent of Supermind in the bodily physical. As I said, it looks as though the Mind of Light is Sri Aurobindo’s creation; it is Sri Aurobindo’s own formulation as a necessary step towards the divinisation of the material. ~ RYD