Brahma Sutras – According to Shankara 3-3 9-10
Topic 9 - Rinsing the mouth is not enjoined in the Prāṇa Vidyā, but only thinking the water as the dress of Prāṇa
कार्याख्यानादपूर्वम् ॥ १८ ॥
kāryākhyānādapūrvam || 18 ||
kāryākhyānāt—On account, of being a restatement of an act (already enjoined by the Smriti); apūrvam—what has not been so enjoined elsewhere.
18. On account of (the rinsing of the mouth with water referred to in the Prāṇa Vidyā) being a restatement of an act (already enjoined by the Smriti), what has not been so enjoined elsewhere (is here enjoined by the Śruti).
In the Chāṇḍogya 5.2.2 and the Brihadāraṇyaka 6.1.14 we find a reference to the rinsing of the mouth with water before and after a meal, thinking that thereby Prāṇa is dressed. The question is whether the Śruti enjoins both or only the latter.
The Sutra states that since the former, the act of rinsing, is already enjoined on every one by the Smriti, the latter act of thinking the water as the dress of Prāṇa is alone enjoined by the Śruti.
Topic 10 - Vidyās in the same Śākhā which are identical or similar have to be combined, for they are one
समान एवञ्च, अभेदात् ॥ १९ ॥
samāna evañca, abhedāt || 19 ||
samāne—In the same Śākhā; evam—(it is) like this; ca—also; abhedāt—on account of non-difference.
19. In the same Śākhā also (it is) like this (i.e. there is unity of Vidyā), on account of the non-difference (of the object of meditation).
In the Agnirahasya in the Vājasaneyi Śākhā there is a Vidyā called Śāndilya Vidyā, in which occurs the passage, “Let him meditate on the Self which consists of mind” etc. (Sat. Br. Madhy. 10.6.3.2).
Again in-the Brihadāraṇyaka, which belongs to the same Śākhā we have, “This Being identified with the mind” etc. (Brih. 5.6.1).
Do these two passages form one Vidyā, in which the particulars mentioned in either text are to be combined, or are they different Vidyās?
The Sutra says that they are one Vidyā, since the object of meditation in both cases is the Self consisting of mind.
The rule as regards the combining of particulars of a similar Vidyā in the same Śākhā is the same as in the case of such Vidyās occurring in different Śākhās. Therefore the Śāndilya Vidyā is one.