or by the philosophers, i.e. by all, or most, or the most notable of
them; or opinions contrary to those that seem to be generally held;
and, again, all opinions that are in accordance with the arts. We must
make propositions also of the contradictories of opinions contrary
to those that seem to be generally held, as was laid down before. It
is useful also to make them by selecting not only those opinions
that actually are accepted, but also those that are like these, e.g.
'The perception of contraries is the same'-the knowledge of them being
so-and 'we see by admission of something into ourselves, not by an
emission'; for so it is, too, in the case of the other senses; for
in hearing we admit something into ourselves; we do not emit; and we
taste in the same way. Likewise also in the other cases. Moreover, all
statements that seem to be true in all or in most cases, should be
taken as a principle or accepted position; for they are posited by
those who do not also see what exception there may be. We should
select also from the written handbooks of argument, and should draw up
sketch-lists of them upon each several kind of subject, putting them
down under separate headings, e.g. 'On Good', or 'On Life'-and that
'On Good' should deal with every form of good, beginning with the
category of essence. In the margin, too, one should indicate also
the opinions of individual thinkers, e.g. 'Empedocles said that the
elements of bodies were four': for any one might assent to the
saying of some generally accepted authority.

  Of propositions and problems there are-to comprehend the matter in
outline-three divisions: for some are ethical propositions, some are
on natural philosophy, while some are logical. Propositions such as
the following are ethical, e.g. 'Ought one rather to obey one's
parents or the laws, if they disagree?'; such as this are logical,
e.g. 'Is the knowledge of opposites the same or not?'; while such as
this are on natural philosophy, e.g. 'Is the universe eternal or not?'
Likewise also with problems. The nature of each of the aforesaid kinds
of proposition is not easily rendered in a definition, but we have
to try to recognize each of them by means of the familiarity
attained through induction, examining them in the light of the
illustrations given above.

  For purposes of philosophy we must treat of these things according
to their truth, but for dialectic only with an eye to general opinion.
All propositions should be taken in their most universal form; then,
the one should be made into many. E.g. 'The knowledge of opposites
is the same'; next, 'The knowledge of contraries is the same', and
that 'of relative terms'. In the same way these two should again be
divided, as long as division is possible, e.g. the knowledge of
'good and evil', of 'white and black', or 'cold and hot'. Likewise
also in other cases.

                                15

  On the formation, then, of propositions, the above remarks are
enough. As regards the number of senses a term bears, we must not only
treat of those terms which bear different senses, but we must also try
to render their definitions; e.g. we must not merely say that
justice and courage are called 'good' in one sense, and that what
conduces to vigour and what conduces to health are called so in
another, but also that the former are so called because of a certain
intrinsic quality they themselves have, the latter because they are
productive of a certain result and not because of any intrinsic
quality in themselves. Similarly also in other cases.

  Whether a term bears a number of specific meanings or one only,
may be considered by the following means. First, look and see if its
contrary bears a number of meanings, whether the discrepancy between
them be one of kind or one of names. For in some cases a difference is
at once displayed even in the names; e.g. the contrary of 'sharp' in
the case of a note is 'flat', while in the case of a solid edge it
is 'dull'. Clearly, then, the contrary of 'sharp' bears several
meanings, and if so, also does 'sharp'; for corresponding to each of
the former terms the meaning of its contrary will be different. For
'sharp' will not be the same when contrary to 'dull' and to 'flat',
though 'sharp' is the contrary of each. Again Barhu ('flat',
'heavy') in the case of a note has 'sharp' as its contrary, but in the
case of a solid mass 'light', so that Barhu is used with a number of
meanings, inasmuch as its contrary also is so used. Likewise, also,
'fine' as applied to a picture has 'ugly' as its contrary, but, as
applied to a house, 'ramshackle'; so that 'fine' is an ambiguous term.

  In some cases there is no discrepancy of any sort in the names used,
but a difference of kind between the meanings is at once obvious: e.g.
in the case of 'clear' and 'obscure': for sound is called 'clear'
and 'obscure', just as 'colour' is too. As regards the names, then,
there is no discrepancy, but the difference in kind between the
meanings is at once obvious: for colour is not called 'clear' in a
like sense to sound. This is plain also through sensation: for of
things that are the same in kind we have the same sensation, whereas
we do not judge clearness by the same sensation in the case of sound
and of colour, but in the latter case we judge by sight, in the former
by hearing. Likewise also with 'sharp' and 'dull' in regard to
flavours and solid edges: here in the latter case we judge by touch,
but in the former by taste. For here again there is no discrepancy
in the names used, in the case either of the original terms or of
their contraries: for the contrary also of sharp in either sense is
'dull'.

  Moreover, see if one sense of a term has a contrary, while another
has absolutely none; e.g. the pleasure of drinking has a contrary in
the pain of thirst, whereas the pleasure of seeing that the diagonal
is incommensurate with the side has none, so that 'pleasure' is used
in more than one sense. To 'love' also, used of the frame of mind, has
to 'hate' as its contrary, while as used of the physical activity