The Complete Aristotle (eng.)

though actually so, may quite easily be
otherwise; for he believes that such is the proper object of
opinion, while the necessary is the object of knowledge.
    In what sense, then, can the same thing be the object of both
opinion and knowledge? And if any one chooses to maintain that all
that he knows he can also opine, why should not opinion be
knowledge? For he that knows and he that opines will follow the
same train of thought through the same middle terms until the
immediate premisses are reached; because it is possible to opine
not only the fact but also the reasoned fact, and the reason is the
middle term; so that, since the former knows, he that opines also
has knowledge.
    The truth perhaps is that if a man grasp truths that cannot be
other than they are, in the way in which he grasps the definitions
through which demonstrations take place, he will have not opinion
but knowledge: if on the other hand he apprehends these attributes
as inhering in their subjects, but not in virtue of the subjects’
substance and essential nature possesses opinion and not genuine
knowledge; and his opinion, if obtained through immediate
premisses, will be both of the fact and of the reasoned fact; if
not so obtained, of the fact alone. The object of opinion and
knowledge is not quite identical; it is only in a sense identical,
just as the object of true and false opinion is in a sense
identical. The sense in which some maintain that true and false
opinion can have the same object leads them to embrace many strange
doctrines, particularly the doctrine that what a man opines falsely
he does not opine at all. There are really many senses of
‘identical’, and in one sense the object of true and false opinion
can be the same, in another it cannot. Thus, to have a true opinion
that the diagonal is commensurate with the side would be absurd:
but because the diagonal with which they are both concerned is the
same, the two opinions have objects so far the same: on the other
hand, as regards their essential definable nature these objects
differ. The identity of the objects of knowledge and opinion is
similar. Knowledge is the apprehension of, e.g. the attribute
‘animal’ as incapable of being otherwise, opinion the apprehension
of ‘animal’ as capable of being otherwise-e.g. the apprehension
that animal is an element in the essential nature of man is
knowledge; the apprehension of animal as predicable of man but not
as an element in man’s essential nature is opinion: man is the
subject in both judgements, but the mode of inherence differs.
    This also shows that one cannot opine and know the same thing
simultaneously; for then one would apprehend the same thing as both
capable and incapable of being otherwise-an impossibility.
Knowledge and opinion of the same thing can co-exist in two
different people in the sense we have explained, but not
simultaneously in the same person. That would involve a man’s
simultaneously apprehending, e.g. (1) that man is essentially
animal-i.e. cannot be other than animal-and (2) that man is not
essentially animal, that is, we may assume, may be other than
animal.
    Further consideration of modes of thinking and their
distribution under the heads of discursive thought, intuition,
science, art, practical wisdom, and metaphysical thinking, belongs
rather partly to natural science, partly to moral philosophy.
34
    Quick wit is a faculty of hitting upon the middle term
instantaneously. It would be exemplified by a man who saw that the
moon has her bright side always turned towards the sun, and quickly
grasped the cause of this, namely that she borrows her light from
him; or observed somebody in conversation with a man of wealth and
divined that he was borrowing money, or that the friendship of
these people sprang from a common enmity. In all these instances he
has seen the major and minor terms and then grasped the causes, the
middle terms.
    Let A represent ‘bright side turned sunward’, B ‘lighted from
the sun’, C the moon. Then B, ‘lighted from the sun’ is predicable
of C, the moon, and A, ‘having her bright side towards the source
of her light’, is predicable of B. So A is predicable of C through
B.

Posterior Analytics, Book II
    Translated by G. R. G. Mure
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1
    The kinds of question we ask are as many as the kinds of things
which we know. They are in fact four:-(1) whether the connexion of
an attribute with a thing is a fact, (2) what is the reason of