sequents, nor deduce a negative through an universal consequent, for it must be in one, and not in the other.
That other modes of speculation also, as regards selection, are useless for the construction of syllogism is apparent; for instance, if the consequents to each are identical, or if those which A (the predicate) follows, and which cannot be with E (the subject), or again those which cannot concur to be with either, for no syllogism arises through these. If then the consequents are identical, as B and F, the middle figure is produced, having both premises affirmative; but if those which A follows, and which cannot be with E, as C and H, there will be the first figure having the minor premise negative; again, if those are identical which cannot be with either, as D and H, both propositions will be negative, either in the first or in the middle figure: thus, however, there will by no means be a syllogism.
We see moreover that we must assume in speculation things identical, and not what are different, or contrary; first, because our inspection is for the sake of the middle, and we must take as a middle, not what is different, but what is identical. Next, in whatever a syllogism happens to be produced, from the assumption of contraries, or of those things which cannot be with the same, all are reduced to the before-named modes, as if B and F are contraries, or cannot be with the same thing; if these are assumed there will be a syllogism that A is with no E: this however does not result from them, but from the above-named mode; for B is with every A, and with no E, so that B must necessarily be identical with a certain H. Again, if B and G do not concur to be with the same thing, (it will follow) that A will not be with a certain E, and so there will be the middle figure, for B is
