Prior Analytics - Book II   

principle he receives a knowledge of the particulars, by an act (as it

were) of recognition. For we know some things directly; e.g. that

the angles are equal to two right angles, if we know that the figure

is a triangle. Similarly in all other cases.

By a knowledge of the universal then we see the particulars, but

we do not know them by the kind of knowledge which is proper to

them; consequently it is possible that we may make mistakes about

them, but not that we should have the knowledge and error that are

contrary to one another: rather we have the knowledge of the universal

but make a mistake in apprehending the particular. Similarly in the

cases stated above. The error in respect of the middle term is not

contrary to the knowledge obtained through the syllogism, nor is the

thought in respect of one middle term contrary to that in respect of

the other. Nothing prevents a man who knows both that A belongs to the

whole of B, and that B again belongs to C, thinking that A does not

belong to C, e.g. knowing that every mule is sterile and that this

is a mule, and thinking that this animal is with foal: for he does not

know that A belongs to C, unless he considers the two propositions

together. So it is evident that if he knows the one and does not

know the other, he will fall into error. And this is the relation of

knowledge of the universal to knowledge of the particular. For we know

no sensible thing, once it has passed beyond the range of our

senses, even if we happen to have perceived it, except by means of the

universal and the possession of the knowledge which is proper to the

particular, but without the actual exercise of that knowledge. For

to know is used in three senses: it may mean either to have

knowledge of the universal or to have knowledge proper to the matter

in hand or to exercise such knowledge: consequently three kinds of

error also are possible. Nothing then prevents a man both knowing

and being mistaken about the same thing, provided that his knowledge

and his error are not contrary. And this happens also to the man whose

knowledge is limited to each of the premisses and who has not