The Vedanta Sutras, commentary by Sankaracharya (SBE34), tr. by George Thibaut  at sacred-texts.com
19. And, moreover, it (i.e. Scripture) teaches the joining of this (i.e. the individual soul) with that, (i.e. the Self consisting of bliss), on that (being fully known).
And for the following reason also the term, 'the Self consisting of bliss,' cannot denote either the pradhâna or the individual soul. Scripture teaches that the individual soul when it has reached knowledge is joined, i.e. identified, with the Self of bliss under discussion, i.e. obtains final release. Compare the following passage (Taitt. Up. II, 7), 'When he finds freedom from fear, and rest in that which is invisible, incorporeal, undefined, unsupported, then he has obtained the fearless. For if he makes but the smallest distinction in it there is fear for him.' That means, if he sees in that Self consisting of bliss even a small difference in the form of non-identity, then he finds no release from the fear of transmigratory existence. But when he, by means of the cognition of absolute identity, finds absolute rest in the Self consisting of bliss, then he is freed from the fear of transmigratory existence. But this (finding absolute rest) is possible only when we understand by the Self consisting of bliss, the highest Self, and not either the pradhâna or the individual soul. Hence it is proved that the Self consisting of bliss is the highest Self.
But, in reality, the following remarks have to be made concerning the true meaning of the word 'ânandamaya 1.' On what grounds, we ask, can it be maintained that the
affix 'maya' after having, in the series of compounds beginning with annamaya and ending with vigñânamaya, denoted mere modifications, should all at once, in the word ânandamaya, which belongs to the same series, denote abundance, so that ânandamaya would refer to Brahman? If it should be said that the assumption is made on account of the governing influence of the Brahman proclaimed in the mantra (which forms the beginning of the chapter, Taitt. Up. II), we reply that therefrom it would follow that also the Selfs consisting of food, breath, &c., denote Brahman (because the governing influence of the mantra extends to them also).--The advocate of the former interpretation will here, perhaps, restate an argument already made use of above, viz. as follows: To assume that the Selfs consisting of food, and so on, are not Brahman is quite proper, because after each of them an inner Self is mentioned. After the Self of bliss, on the other hand, no further inner Self is mentioned, and hence it must be considered to be Brahman itself; otherwise we should commit the mistake of dropping the subject-matter in hand (as which Brahman is pointed out by the mantra), and taking up a new topic.--But to this we reply that, although unlike the case of the Selfs consisting of food, &c., no inner Self is mentioned after the Self consisting of bliss, still the latter cannot be considered as Brahman, because with reference to the Self consisting of bliss Scripture declares, 'Joy is its head. Satisfaction is its right arm. Great satisfaction is its left arm. Bliss is its trunk. Brahman is its tail, its support.' Now, here the very same Brahman which, in the mantra, had been introduced as the subject of the discussion, is called the tail, the support; while the five involucra, extending from the involucrum of food up to the involucrum of bliss, are merely introduced for the purpose of setting forth the knowledge of Brahman. How, then, can it be maintained that our interpretation implies the needless dropping of the general subject-matter and the introduction of a new topic?--But, it may again be objected, Brahman is called the tail, i.e. a member of the Self consisting of bliss; analogously to those passages in which a tail and
other members are ascribed to the Selfs consisting of food and so on. On what grounds, then, can we claim to know that Brahman (which is spoken of as a mere member, i.e. a subordinate matter) is in reality the chief matter referred to?--From the fact, we reply, of Brahman being the general subject-matter of the chapter.--But, it will again be said, that interpretation also according to which Brahman is cognised as a mere member of the ânandamaya does not involve a dropping of the subject-matter, since the ânandamaya himself is Brahman.--But, we reply, in that case one and the same Brahman would at first appear as the whole, viz. as the Self consisting of bliss, and thereupon as a mere part, viz. as the tail; which is absurd. And as one of the two alternatives must be preferred, it is certainly appropriate to refer to Brahman the clause 'Brahman is the tail' which contains the word 'Brahman,' and not the sentence about the Self of Bliss in which Brahman is not mentioned. Moreover, Scripture, in continuation of the phrase, 'Brahman is the tail, the support,' goes on, 'On this there is also the following sloka: He who knows the Brahman as non-existing becomes himself non-existing. He who knows Brahman as existing him we know himself as existing.' As this sloka, without any reference to the Self of bliss, states the advantage and disadvantage connected with the knowledge of the being and non-being of Brahman only, we conclude that the clause, 'Brahman is the tail, the support,' represents Brahman as the chief matter (not as a merely subordinate matter). About the being or non-being of the Self of bliss, on the other hand, a doubt is not well possible, since the Self of bliss distinguished by joy, satisfaction, &c., is well known to every one.--But if Brahman is the principal matter, how can it be designated as the mere tail of the Self of bliss ('Brahman is the tail, the support')?--Its being called so, we reply, forms no objection; for the word tail here denotes that which is of the nature of a tail, so that we have to understand that the bliss of Brahman is not a member (in its literal sense), but the support or abode, the one nest (resting-place) of all worldly bliss. Analogously another
scriptural passage declares, 'All other creatures live on a small portion of that bliss' (Bri. Up. IV, 3, 32). Further, if by the Self consisting of bliss we were to understand Brahman we should have to assume that the Brahman meant is the Brahman distinguished by qualities (savisesha), because it is said to have joy and the like for its members. But this assumption is contradicted by a complementary passage (II, 9) which declares that Brahman is the object neither of mind nor speech, and so shows that the Brahman meant is the (absolute) Brahman (devoid of qualities), 'From whence all speech, with the mind, turns away unable to reach it, he who knows the bliss of that Brahman fears nothing.' Moreover, if we speak of something as 'abounding in bliss 1,' we thereby imply the co-existence of pain; for the word 'abundance' in its ordinary sense implies the existence of a small measure of what is opposed to the thing whereof there is abundance. But the passage so understood would be in conflict with another passage (Kh. Up. VII, 24), 'Where one sees nothing else, hears nothing else, understands nothing else, that is the Infinite;' which declares that in the Infinite, i.e. Brahman, there is nothing whatever different from it. Moreover, as joy, &c. differ in each individual body, the Self consisting of bliss also is a different one in each body. Brahman, on the other hand, does not differ according to bodies; for the mantra at the beginning of the chapter declares it to be true Being, knowledge, infinite, and another passage says, 'He is the one God, hidden in all beings, all-pervading, the Self within all beings' (Sv. Up. VI, 11). Nor, again, does Scripture exhibit a frequent repetition of the word 'ânandamaya;' for merely the radical part of the compound (i.e. the word ânanda without the affix maya) is repeated in all the following passages; 'It is a flavour, for only after seizing flavour can any one seize bliss. Who could breathe, who could breathe forth, if that bliss existed not in the ether? For he alone causes blessedness;' 'Now this is an examination of bliss;' 'He who
knows the bliss of that Brahman fears nothing;' 'He understood that bliss is Brahman.' If it were a settled matter that Brahman is denoted by the term, 'the Self consisting of bliss,' then we could assume that in the subsequent passages, where merely the word 'bliss' is employed, the term 'consisting of bliss' is meant to be repeated; but that the Self consisting of bliss is not Brahman, we have already proved by means of the reason of joy being its head, and so on. Hence, as in another scriptural passage, viz. 'Brahman is knowledge and bliss' (Bri. Up. III, 9, 28), the mere word 'bliss' denotes Brahman, we must conclude that also in such passages as, 'If that bliss existed not in the ether,' the word bliss is used with reference to Brahman, and is not meant to repeat the term 'consisting of bliss.' The repetition of the full compound, 'consisting of bliss,' which occurs in the passage, 'He reaches that Self consisting of bliss' (Taitt. Up. II, 8), does not refer to Brahman, as it is contained in the enumeration of Non-Selfs, comprising the Self of food, &c., all of which are mere effects, and all of which are represented as things to be reached.--But, it may be said, if the Self consisting of bliss, which is said to have to be reached, were not Brahman--just as the Selfs consisting of food, &c. are not Brahman--then it would not be declared (in the passage immediately following) that he who knows obtains for his reward Brahman.--This objection we invalidate by the remark that the text makes its declaration as to Brahman--which is the tail, the support--being reached by him who knows, by the very means of the declaration as to the attainment of the Self of bliss; as appears from the passage, 'On this there is also this sloka, from which all speech returns,' &c. With reference, again, to the passage, 'He desired: may I be many, may I grow forth,' which is found in proximity to the mention of the Self consisting of bliss, we remark that it is in reality connected (not with the Self of bliss but with) Brahman, which is mentioned in the still nearer passage, 'Brahman is the tail, the support,' and does therefore not intimate that the Self of bliss is Brahman. And, on account of its referring to the passage last quoted ('it desired,' &c.), the later passage
also, 'That is flavour,' &c., has not the Self of bliss for its subject.--But, it may be objected, the (neuter word) Brahman cannot possibly be designated by a masculine word as you maintain is done in the passage, 'He desired,' &c.--In reply to this objection we point to the passage (Taitt. Up. II, 1), 'From that Self sprang ether,' where, likewise, the masculine word 'Self' can refer to Brahman only, since the latter is the general topic of the chapter. In the knowledge of Bhrigu and Varuna finally ('he knew that bliss is Brahman'), the word 'bliss' is rightly understood to denote Brahman, since we there meet neither with the affix 'maya,' nor with any statement as to joy being its head, and the like. To ascribe to Brahman in itself joy, and so on, as its members, is impossible, unless we have recourse to certain, however minute, distinctions qualifying Brahman; and that the whole chapter is not meant to convey a knowledge of the qualified (savisesha) Brahman is proved by the passage (quoted above), which declares that Brahman transcends speech and mind. We therefore must conclude that the affix maya, in the word ânandamaya, does not denote abundance, but expresses a mere effect, just as it does in the words annamaya and the subsequent similar compounds.
The Sûtras are therefore to be explained as follows. There arises the question whether the passage, 'Brahman is the tail, the support,' is to be understood as intimating that Brahman is a mere member of the Self consisting of bliss, or that it is the principal matter. If it is said that it must be considered as a mere member, the reply is, 'The Self consisting of bliss on account of the repetition.' That means: Brahman, which in the passage 'the Self consisting of bliss,' &c., is spoken of as the tail, the support, is designated as the principal matter (not as something subordinate). On account of the repetition; for in the memorial sloka, 'he becomes himself non-existing,' Brahman alone is reiterated. 'If not, on account of the word denoting a modification; not so, on account of abundance.' In this Sûtra the word 'modification' is meant to convey the sense of member. The objection that on account of
the word 'tail,' which denotes a mere member, Brahman cannot be taken as the principal matter must be refuted. This we do by remarking that there is no difficulty, since a word denoting a member may be introduced into the passage on account of prâkurya 1. Prâkurya here means a phraseology abounding in terms denoting members. After the different members, beginning with the head and ending with the tail, of the Selfs, consisting of food, &c. have been enumerated, there are also mentioned the head and the other limbs of the Self of bliss, and then it is added, 'Brahman is the tail, the support;' the intention being merely to introduce some more terms denoting members, not to convey the meaning of 'member,' (an explanation which is impossible) because the preceding Sûtra already has proved Brahman (not to be a member, but) to be the principal matter. 'And because he is declared to be the cause of it.' That means: Brahman is declared to be the cause of the entire aggregate of effects, inclusive of the Self, consisting of bliss, in the following passage, 'He created all whatever there is' (Taitt. Up. II, 6). And as Brahman is the cause, it cannot at the same time be called the member, in the literal sense of the word, of the Self of bliss, which is nothing but one of Brahman's effects. The other Sûtras also (which refer to the Self of bliss 2) are to be considered, as well as they may, as conveying a knowledge of Brahman, which (Brahman) is referred to in the passage about the tail.
71:1 The explanation of the ânandamaya given hitherto is here recalled, and a different one given. The previous explanation is attributed by Go. Ân. to the vrittikâra.
74:1 In which sense, as shown above, the word ânandamaya must be taken if understood to denote Brahman.
77:1 I.e. the word translated hitherto by abundance.
77:2 See I, 1, 15-19.