The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
51. Not also on account of its resembling (the mânasa cup) (can the fires constitute parts of an action); for it is observed (on the ground of Sruti, &c., that they are independent); as in the case of death; for the world does not become (a fire) (because it resembles a fire in some points).
Against the allegation made by the pûrvapakshin that the present case is analogous to that of the mânasa cup, we
remark that the fire-altars made of mind and so on cannot be assumed to supplement a sacrificial action although they may resemble the mânasa cup, since on the ground of direct enunciation &c. they are seen to subserve the purpose of man only (not the purpose of some sacrificial action). Anything indeed may resemble anything in some point or other; but in spite of that there remains the individual dissimilarity of each thing from all other things. The case is analogous to that of death. In the passages, 'The man in that orb is death indeed' (Sat. Brâ. X, 5, 2, 3), and 'Agni indeed is death' (Taitt. Samh. V, i, 10, 3), the term 'death' is applied equally to Agni and the man in the sun; all the same the two are by no means absolutely equal. And if the text says in another place, 'This world is a fire indeed, O Gotama; the sun is its fuel,' &c. (Kh. Up. V, 4, i), it does not follow from the similarity of fuel and so on that the world really is a fire. Thus also in our case.