The Complete Aristotle (eng.)

the
connexion, (3) whether a thing exists, (4) What is the nature of
the thing. Thus, when our question concerns a complex of thing and
attribute and we ask whether the thing is thus or otherwise
qualified-whether, e.g. the sun suffers eclipse or not-then we are
asking as to the fact of a connexion. That our inquiry ceases with
the discovery that the sun does suffer eclipse is an indication of
this; and if we know from the start that the sun suffers eclipse,
we do not inquire whether it does so or not. On the other hand,
when we know the fact we ask the reason; as, for example, when we
know that the sun is being eclipsed and that an earthquake is in
progress, it is the reason of eclipse or earthquake into which we
inquire.
    Where a complex is concerned, then, those are the two questions
we ask; but for some objects of inquiry we have a different kind of
question to ask, such as whether there is or is not a centaur or a
God. (By ‘is or is not’ I mean ‘is or is not, without further
qualification’; as opposed to ‘is or is not [e.g.] white’.) On the
other hand, when we have ascertained the thing’s existence, we
inquire as to its nature, asking, for instance, ‘what, then, is
God?’ or ‘what is man?’.
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    These, then, are the four kinds of question we ask, and it is in
the answers to these questions that our knowledge consists.
    Now when we ask whether a connexion is a fact, or whether a
thing without qualification is, we are really asking whether the
connexion or the thing has a ‘middle’; and when we have ascertained
either that the connexion is a fact or that the thing is-i.e.
ascertained either the partial or the unqualified being of the
thing-and are proceeding to ask the reason of the connexion or the
nature of the thing, then we are asking what the ‘middle’ is.
    (By distinguishing the fact of the connexion and the existence
of the thing as respectively the partial and the unqualified being
of the thing, I mean that if we ask ‘does the moon suffer
eclipse?’, or ‘does the moon wax?’, the question concerns a part of
the thing’s being; for what we are asking in such questions is
whether a thing is this or that, i.e. has or has not this or that
attribute: whereas, if we ask whether the moon or night exists, the
question concerns the unqualified being of a thing.)
    We conclude that in all our inquiries we are asking either
whether there is a ‘middle’ or what the ‘middle’ is: for the
‘middle’ here is precisely the cause, and it is the cause that we
seek in all our inquiries. Thus, ‘Does the moon suffer eclipse?’
means ‘Is there or is there not a cause producing eclipse of the
moon?’, and when we have learnt that there is, our next question
is, ‘What, then, is this cause? for the cause through which a thing
is-not is this or that, i.e. has this or that attribute, but
without qualification is-and the cause through which it is-not is
without qualification, but is this or that as having some essential
attribute or some accident-are both alike the middle’. By that
which is without qualification I mean the subject, e.g. moon or
earth or sun or triangle; by that which a subject is (in the
partial sense) I mean a property, e.g. eclipse, equality or
inequality, interposition or non-interposition. For in all these
examples it is clear that the nature of the thing and the reason of
the fact are identical: the question ‘What is eclipse?’ and its
answer ‘The privation of the moon’s light by the interposition of
the earth’ are identical with the question ‘What is the reason of
eclipse?’ or ‘Why does the moon suffer eclipse?’ and the reply
‘Because of the failure of light through the earth’s shutting it
out’. Again, for ‘What is a concord? A commensurate numerical ratio
of a high and a low note’, we may substitute ‘What ratio makes a
high and a low note concordant? Their relation according to a
commensurate numerical ratio.’ ‘Are the high and the low note
concordant?’ is equivalent to ‘Is their ratio commensurate?’; and
when we find that it is commensurate, we ask ‘What, then, is their
ratio?’.
    Cases in which the ‘middle’ is sensible show that the object of
our inquiry is always the ‘middle’: we inquire, because we have not
perceived it, whether there is or is not a ‘middle’ causing, e.g.
an eclipse. On the other hand, if we were on the moon we should not
be inquiring either as to the fact or the reason, but both fact