The Complete Aristotle (eng.)

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some it is not: for whether it be shown that all pleasure, or that
no pleasure, is good, the proposition in question will have been
demolished. If, however, he has stated that only one single
pleasure is good, it is possible to demolish it in three ways: for
by showing that all pleasure, or that no pleasure, or that more
than one pleasure, is good, we shall have demolished the statement
in question. If the statement be made still more definite, e.g.
that prudence alone of the virtues is knowledge, there are four
ways of demolishing it: for if it be shown that all virtue is
knowledge, or that no virtue is so, or that some other virtue (e.g.
justice) is so, or that prudence itself is not knowledge, the
proposition in question will have been demolished.
    It is useful also to take a look at individual instances, in
cases where some attribute has been said to belong or not to
belong, as in the case of universal questions. Moreover, you should
take a glance among genera, dividing them by their species until
you come to those that are not further divisible, as has been said
before:’ for whether the attribute is found to belong in all cases
or in none, you should, after adducing several instances, claim
that he should either admit your point universally, or else bring
an objection showing in what case it does not hold. Moreover, in
cases where it is possible to make the accident definite either
specifically or numerically, you should look and see whether
perhaps none of them belongs, showing e.g. that time is not moved,
nor yet a movement, by enumerating how many species there are of
movement: for if none of these belong to time, clearly it does not
move, nor yet is a movement. Likewise, also, you can show that the
soul is not a number, by dividing all numbers into either odd or
even: for then, if the soul be neither odd nor even, clearly it is
not a number.
    In regard then to Accident, you should set to work by means like
these, and in this manner.

Topics, Book IV
    Translated by W. A. Pickard-Cambridge
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    div id="book4" class="book" title="Book IV">
    1
    Next we must go on to examine questions relating to Genus and
Property. These are elements in the questions that relate to
definitions, but dialecticians seldom address their inquiries to
these by themselves. If, then, a genus be suggested for something
that is, first take a look at all objects which belong to the same
genus as the thing mentioned, and see whether the genus suggested
is not predicated of one of them, as happens in the case of an
accident: e.g. if ‘good’ be laid down to be the genus of
‘pleasure’, see whether some particular pleasure be not good: for,
if so, clearly good’ is not the genus of pleasure: for the genus is
predicated of all the members of the same species. Secondly, see
whether it be predicated not in the category of essence, but as an
accident, as ‘white’ is predicated of ‘snow’, or ‘self-moved’ of
the soul. For ‘snow’ is not a kind of ‘white’, and therefore
‘white’ is not the genus of snow, nor is the soul a kind of ‘moving
object’: its motion is an accident of it, as it often is of an
animal to walk or to be walking. Moreover, ‘moving’ does not seem
to indicate the essence, but rather a state of doing or of having
something done to it. Likewise, also, ‘white’: for it indicates not
the essence of snow, but a certain quality of it. So that neither
of them is predicated in the category of ‘essence’.
    Especially you should take a look at the definition of Accident,
and see whether it fits the genus mentioned, as (e.g.) is also the
case in the instances just given. For it is possible for a thing to
be and not to be self-moved, and likewise, also, for it to be and
not to be white. So that neither of these attributes is the genus
but an accident, since we were saying that an accident is an
attribute which can belong to a thing and also not belong.
    Moreover, see whether the genus and the species be not found in
the same division, but the one be a substance while the other is a
quality, or the one be a relative while the other is a quality, as
(e.g.) ‘slow’ and ‘swan’ are each a substance, while ‘white’ is not
a substance but a quality, so that ‘white’ is not the genus either
of ‘snow’ or of ‘swan’. Again, knowledge’ is a relative, while
‘good’ and ‘noble’ are each a quality, so that good, or noble, is
not the genus of knowledge. For the genera of relatives