Madhvaon Brahma Sūtra 2.4.5

The number * seven * is stated with reference to the intellectual organs, as it is so qualified in the text, “ In every person there are seven (organs) constituted for the purpose of (producing) knowledge (Ath. II. i. 8). By the term ‘ also/ the statement in the Bhavishyat Parvan is referred to, which is: “ There are seven breaths or organs as means of knowledge, while there are five breaths or organs as instruments of action. Thus the group of twelve organs or breaths is always established in the body.”