We are permitted, and it is often convenient, to exchange one phrase or term for another of equivalent signification, and also one word against any equivalent phrase. By doing this, we often **facilitate the setting out of the terms. We must carefully note the different meanings of the same substantive noun, according as the definite article is or is not prefixed. We must not reckon it the same term, if it appears in one premiss with the definite article, and in the other without the definite article.[81] Nor is it the same proposition to say B is predicable of C (indefinite), and B is predicable of _all_ C (universal). In setting out the syllogism, it is not sufficient that the major premiss should be indefinite; the major premiss must be universal; and the minor premiss also, if the conclusion is to be universal. If the major premiss be universal, while the minor premiss is only affirmative indefinite, the conclusion cannot be universal, but will be no more than indefinite, that is, counting as particular.[82] [Footnote 81: Analyt. Prior. I. xxxix.-xl. p. 49, b. 3-13. [Greek: ou) tau)to\n e)sti to\ ei)=nai tê\n ê(donê\n a)gatho\n kai\ to\ ei)=nai tê\n ê(donê\n to\ a)gatho/n], &c.] [Footnote 82: Ibid. I. xli. p. 49, b. 14-32. The Scholion of Alexander (Schol. p. 184, a. 22-40) alludes to the peculiar mode, called by Theophrastus [Greek: kata\ pro/slêpsin], of stating the premisses of the syllogism: two terms only, the major and the middle, being enunciated, while the third or minor was included potentially, but not enunciated. Theophrastus, however, did not recognize the distinction of meaning to which Aristotle alludes in this chapter. He construed as an universal minor, what Aristotle treats as only an indefinite minor. The liability to mistake the Indefinite for an Universal is here again adverted to.] There is no fear of our being misled by setting out a particular case for the purpose of the general demonstration; for we never make reference to the specialties of the particular case, but deal with it as the geometer deals with the diagram that he draws. He calls the line A B, straight, a foot long, and without breadth, but he does not draw any conclusion from these assumptions. All that syllogistic demonstration either requires or employs, is, terms that are related to each other either as whole to part or as part to whole. Without this, no demonstration can be made: the exposition of the particular case is intended as an appeal to the senses, for facilitating the march of the student, but is not essential to demonstration.[83] [Footnote 83: Ibid. I. xli. p. 50, a. 1: [Greek: tô=| d' e)kti/thesthai ou(/tô chrô/metha ô(/sper kai\ tô=| ai)stha/nesthai to\n mantha/nonta le/gontes; ou) ga\r ou(/tôs ô(s a)/neu tou/tôn ou)ch oi(=o/n t' a)podeichthê=nai, ô(/sper e)x ô(=n o( sullogismo/s.]