vidual, and again C and D likewise, but A follows C and does not reciprocate, D will also follow B, and will not reciprocate, and A and D may be with the same thing, but B and C cannot. In the first place then, it appears from this that D is consequent to B, for since one of C D is necessarily present with every individual, but with what B is present C cannot be, because it introduces with itself A, but A and B cannot consist with the same, D is evidently a consequent. Again, since C does not reciprocate with A, but C or D is present with every, it happens that A and D will be with the same thing, but B and C cannot, because A is consequent to C, for an impossibility results, wherefore it appears plain that neither does B reciprocate with D, because it would happen that A is present together with D.
Sometimes also it occurs that we are deceived not such an arrangement of terms, because of our not taking opposites rightly, one of which must necessarily be with every individual, as if A and B cannot be simultaneously with the same, but it is necessary that the one should be with what the other is not, and again C and D in like manner, but A is consequent to every C; for B will happen necessarily to be with that with which D is, which is false. For let the negative of A B which is F be assumed, and again the negative of C D, and let it be H, it is necessary then, that either A or F should be with every individual, since either affirmation or negation must be present. Again also, either C or H, for they are affirmation and negation, and A is by hypothesis present with every thing with which C is, so that H will also be present with whatever F is. Again, since of F B, one is with every individual, and so also one of H D, and H is consequent to F, B will also be consequent to D, for this we know. If then A is consequent to C, B will also follow D, but this is false, since the sequence was the reverse in things so subsisting, for it is not perhaps necessary that either A or F should be with every individual, neither F nor B, for F is not the negative of A, since of "good" the negation is "not good," and "it is not good" is not the same with "it is neither good nor not good." It is the same also of C D, for the assumed negatives are two.
