Śaṅkaraon Brahma Sūtra 2.4.7

The author of the Sutras adds another characteristic quality of the prawas. The prd;/as under discussion must be viewed as minute. By their minuteness we have to understand subtilty and limited size ; but not atomic size, as otherwise they would be incapable of producing effects which extend over the whole body. They must be subtle; for if they were big the persons surrounding a dying man would see them coming out from the body at the moment of death, as a snake comes out of its hole. They must be limited ; for if they were all-pervading the scriptural statements as to their passing out of the body, going and coming, would be contradicted thereby, and it could not be established that the individual soul is ‘ the essence of the qualities of that’ (i. e. the manas ; cp. II, 3, 29). Should it be said that they may be all-pervading, but at the same time appear as functions (v/'ftti) in the body only, we rejoin that only a function can constitute an instrument. Whatever effects perception, may it be a function or something else, just that is an instrument for us. The disagreement is therefore about a name only, and the assumption of the instruments (prdwas) being all-pervading is thus purposeless. Hence we decide that the prawas are subtle and of limited size.