Ramanujacharya's Brahma Sutra Bhashya translated By George Thibaut
SriBhashya - Ramanuja's Commentary On Brahma Sutra (Vedanta Sutra)

5. Should it be said, on account of absence of mention in the first (reply); we say no, for just that (is meant), on the ground of fitness.

An objection is raised to the conclusion arrived at under III, 1, 1; on the ground that in the first oblation, described in Kh. Up. V, 4, 2, as being made into the heavenly world, water is not mentioned at all as the thing offered. The text says, 'on that altar the gods offer sraddhâ'; and by sraddhâ (belief) everybody understands a certain activity of mind. Water therefore is not the thing offered.--Not so, we reply. It is nothing else but water, which there is called sraddhâ. For thus only question and answer have a sense. For the question is, 'Do you know why in the fifth libation water is called man?' and at the outset of the reply sraddhâ is mentioned as constituting the oblation made into the heavenly world viewed as a fire. If here the word sraddhâ did not denote water, question and answer would refer to different topics, and there would be no connexion. The form in which the final statement is introduced (iti tu pañkamyâm, &c., 'but thus in the fifth oblation,' &c.), moreover, also intimates that sraddhâ means water. The word 'iti,' thus, here intimates that the answer is meant to dispose of the question, 'Do you know how?' &c. Sraddhâ becomes moon, rain, food, seed, embryo in succession, and thus the water comes to be called man. Moreover, the word sraddhâ is actually used in the Veda in the sense of 'water'; 'he carries water, sraddhâ indeed is water' (Taitt. Samh. I, 6, 8, 1). Aad what the text says as

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to king Soma (the moon) originating from sraddhâ when offered, also shows that sraddhâ must mean water.