by Swami Sivananda
The function of mind is merged in Prana.
Tanmanah prana uttarat IV.2.3 (499)
That mind (is merged) in Prana (as is seen) from the subsequent clause (of the Sruti cited).
Tat: that; Manah: mind; Prana: in the Prana; Uttarat: from the subsequent clause (of the Sruti).
It has been shown that the passage "speech is merged in mind" means a merging of the function only. A doubt here arises whether the subsequent clause "mind is breath" also means to intimate a merging of the function only or of that to which the function belongs.
The Purvapakshin maintains that here it is mind itself and not its function that gets merged in Prana, as Prana can be said to be the material cause of mind. In support of his statement he quotes the following text: "Mind consists of food, Prana of water" (Chh. Up. VI.6.5); "Water sent forth earth" (VI.2.4). When mind, therefore, is merged in Prana, it is the same thing as earth being merged in water, for mind is food or earth, and Prana is water, causal substance and effect being non-different. Hence the Sruti here speaks not of the function of the mind, but of mind itself getting merged in Prana.
This Sutra refutes this view. For the same reason it is the mental Vrittis (functions) that get merged in Prana, because in deep sleep and in approaching death, we see the mental functions stopping while the Prana (breath) is active. The mind is not derived from Prana, and hence cannot merge in it. Breath or Prana is not the causal substance of mind. The relation of causality by an indirect process does not suffice to show that mind is really merged in Prana. Were it so, then mind would also be merged in earth, earth in water, breath in water. Nor is there on the alternative contemplated any proof of mind having originated from that water which has passed over into breath.
Therefore, mind cannot itself be merged in Prana. The function of the mind only is merged in Prana.