The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut [1896] at sacred-texts.com
24. If it be said (that the two cases are not parallel), on account of the specialisation of abode (present in the case of the sandal-ointment, absent in the case of the soul); we deny that, on account of the acknowledgment (by scripture, of a special place of the soul), viz. within the heart.
Here it may be objected that the argumentation relied upon in the last Sûtra is not admissible, because the two cases compared are not parallel. If it were a settled matter that the soul dwells in one point of the body, the drop of sandal-ointment might be adduced as a parallel instance. But, as a matter of fact, we know from perception that the drop of sandal-ointment is in contact with one spot of the body only, just as we know that it refreshes the whole body; while in the case of the soul observation tells us only that it is percipient all over the body, but not that it abides in one spot.--Should it be said that the latter point must be settled by inference, we reply that inference is here of no use, because it is not capable of removing the doubt whether the perception extending over the whole body belongs to a soul which extends over the whole body like the skin and the sense of touch inhering in it, or to a soul which is all-pervading like ether, or to a soul which, like a drop of ointment, is minute and abides in one spot only 1.
This objection, the pûrvapakshin replies, is unfounded 'on account of the acknowledgment of a speciality of abode,' an abiding in one spot of the body being admitted in the case of the soul no less than in the case of a drop of ointment. For we read in the Vedânta-texts that the soul abides within the heart; cp. for instance, the information given (in Pr. Up. III, 6),'The Self is in the heart;' (Kh. Up. VIII, 3, 3), 'That Self abides in the heart;' (Bri. Up. IV, 3, 7), 'Who is that Self?--He who is within the heart, surrounded by the Prânas, the person of light, consisting of knowledge.'--As therefore the two cases compared are not devoid of parallelism, the argumentation resorted to in Sûtra 23 is unobjectionable.
39:1 We cannot reason as follows, 'The soul is atomic because it produces effects extending (over the whole body), like a drop of sandal-ointment;' for that reasoning would apply to the sense of touch (the skin) also, which we know not to be of atomic size.