in “Secret of the Vedas” Sri Aurobindo writes:
We find this fundamental idea of the Vedic Rishis brought out in the Hymn of Creation (X.129) where the subconscient is thus described. “Darkness hidden by darkness in the beginning was this all, an ocean without mental consciousness . . . out of it the One was born by the greatness of Its energy. It first moved in it as desire which was the first seed of mind. The Masters of Wisdom found out in the non-existent that which builds up the existent; in the heart they found it by purposeful impulsion and by the thought-mind. Their ray was extended horizontally; there was something above, there was something below.” In this passage the same ideas are brought out as in Vamadeva’s hymn but without the veil of images. Out of the subconscient ocean the One arises in the heart first as desire; he moves there in the heart-ocean as an unexpressed desire of the delight of existence and this desire is the first seed of what afterwards appears as the sense-mind. The gods thus find out a means of building up the existent, the conscious being, out of the subconscient darkness; they find it in the heart and bring it out by the growth of thought and purposeful impulsion, pratīṣyā, by which is meant mental desire as distinguished from the first vague desire that arises out of the subconscient in the merely vital movements of nature. The conscious existence which they thus create is stretched out as it were horizontally between two other extensions; below is the dark sleep of the subconscient, above is the luminous secrecy of the superconscient. These are the upper and the lower ocean.
This Vedic imagery throws a clear light on the similar symbolic images of the Puranas, especially on the famous symbol of Vishnu sleeping after the pralaya on the folds of the snake Ananta upon the ocean of sweet milk.
Sri Aurobindo: Secret of the Vedas pp.106 – 107