The Complete Aristotle (eng.)

either to
two problems or to four. For if he at the same time render this
property of one thing and deny it of another, only two problems
arise, as in the case of a statement that it is a property of a
man, in relation to a horse, to be a biped. For one might try both
to show that a man is not a biped, and also that a horse is a
biped: in both ways the property would be upset. If on the other
hand he render one apiece of two attributes to each of two things,
and deny it in each case of the other, there will then be four
problems; as in the case of a statement that it is a property of a
man in relation to a horse for the former to be a biped and the
latter a quadruped. For then it is possible to try to show both
that a man is not naturally a biped, and that he is a quadruped,
and also that the horse both is a biped, and is not a quadruped. If
you show any of these at all, the intended attribute is
demolished.]
    An ‘essential’ property is one which is rendered of a thing in
comparison with everything else and distinguishes the said thing
from everything else, as does ‘a mortal living being capable of
receiving knowledge’ in the case of man. A ‘relative’ property is
one which separates its subject off not from everything else but
only from a particular definite thing, as does the property which
virtue possesses, in comparison with knowledge, viz. that the
former is naturally produced in more than one faculty, whereas the
latter is produced in that of reason alone, and in those who have a
reasoning faculty. A ‘permanent’ property is one which is true at
every time, and never fails, like being’ compounded of soul and
body’, in the case of a living creature. A ‘temporary’ property is
one which is true at some particular time, and does not of
necessity always follow; as, of some particular man, that he walks
in the market-place.
    To render a property ‘relatively’ to something else means to
state the difference between them as it is found either universally
and always, or generally and in most cases: thus a difference that
is found universally and always, is one such as man possesses in
comparison with a horse, viz. being a biped: for a man is always
and in every case a biped, whereas a horse is never a biped at any
time. On the other hand, a difference that is found generally and
in most cases, is one such as the faculty of reason possesses in
comparison with that of desire and spirit, in that the former
commands, while the latter obeys: for the reasoning faculty does
not always command, but sometimes also is under command, nor is
that of desire and spirit always under command, but also on
occasion assumes the command, whenever the soul of a man is
vicious.
    Of ‘properties’ the most ‘arguable’ are the essential and
permanent and the relative. For a relative property gives rise, as
we said before, to several questions: for of necessity the
questions arising are either two or four, or that arguments in
regard to these are several. An essential and a permanent property
you can discuss in relation to many things, or can observe in
relation to many periods of time: if essential’, discuss it in
comparison with many things: for the property ought to belong to
its subject in comparison with every single thing that is, so that
if the subject be not distinguished by it in comparison with
everything else, the property could not have been rendered
correctly. So a permanent property you should observe in relation
to many periods of time; for if it does not or did not, or is not
going to, belong, it will not be a property. On the other hand,
about a temporary property we do not inquire further than in regard
to the time called ‘the present’; and so arguments in regard to it
are not many; whereas an arguable’ question is one in regard to
which it is possible for arguments both numerous and good to
arise.
    The so-called ‘relative’ property, then, should be examined by
means of the commonplace arguments relating to Accident, to see
whether it belongs to the one thing and not to the other: on the
other hand, permanent and essential properties should be considered
by the following methods.
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2
    First, see whether the property has or has not been rendered
correctly. Of a rendering being incorrect or correct, one test is
to see whether the terms in which the property is stated are not or
are more intelligible-for destructive purposes, whether they