The Vedanta Sutras, commentary by Sankaracharya (SBE34), tr. by George Thibaut [1890] at sacred-texts.com
35. Nor is non-contradiction to be derived from the succession (of parts acceding to and departing from the soul), on account of the change, &c. (of the soul).
Nor can the doctrine of the soul having the same size as the body be satisfactorily established by means of the hypothesis of the successive accession and withdrawal of particles. For this hypothesis would involve the soul's undergoing changes and the like. If the soul is continually being repleted and depleted by the successive addition and withdrawal of parts, it of course follows that it undergoes change, and if it is liable to change it follows that it is non-permanent, like the skin and similar substances. From that, again, it follows that the Gaina doctrine of bondage and release is untenable; according to which doctrine 'the soul, which in the state of bondage is encompassed by the ogdoad of works and sunk in the ocean of samsâra, rises when its bonds are sundered, as the gourd rises to the surface of the water when it is freed from the encumbering clay 1.'--Moreover, those particles which in turns come and depart have the attributes of coming and going, and cannot, on that account, be of the nature of the Self any more than the body is. And if it be said that the Self consists of some permanently remaining parts, we remark that it would be impossible to determine which are the permanent and which the temporary parts.--We have further to ask from whence those particles originate when they accede to the soul, and into what they are merged when they detach themselves from it. They cannot spring from the material elements
and re-enter the elements; for the soul is immaterial. Nor have we any means to prove the existence of some other, general or special, reservoir of soul-particles.--Moreover, on the hypothesis under discussion the soul would be of indefinite nature, as the size of the particles acceding and departing is itself indefinite.--On account of all these and similar difficulties it cannot be maintained that certain particles by turns attach themselves to, and detach themselves from, the soul.
The Sûtra may be taken in a different sense also. The preceding Sûtra has proved that the soul if of the same size as the body cannot be permanent, as its entering into bigger and smaller bodies involves its limitation. To this the Gymnosophist may be supposed to rejoin that although the soul's size successively changes it may yet be permanent, just as the stream of water is permanent (although the water continually changes). An analogous instance would be supplied by the permanency of the stream of ideas while the individual ideas, as that of a red cloth and so on, are non-permanent.--To this rejoinder our Sûtra replies that if the stream is not real we are led back to the doctrine of a general void, and that, if it is something real, the difficulties connected with the soul's changing, &c. present themselves and render the Gaina view impossible.
432:1 Cp. Sarvadarsanasamgraha translation, p. 58.