20. We have to ascertain whether there is not to every quality a contrary. In the case of virtue and vice, even the mean appears to be contrary to the extremes.
But when we turn to colours, we do not find the intermediates so related. If we regard the intermediates as blendings of the extremes, we must not posit any contrariety other than that between black and white, but must show that all other colours are combinations of these two. Contrariety however demands that there be some one distinct quality in the intermediates, though this quality may be seen to arise from a combination.
It may further be suggested that contraries not only differ from each other, but also entail the greatest possible difference. But "the greatest possible difference" would seem to presuppose that intermediates have already been established: eliminate the series, and how will you define "the greatest possible"? Sight, we may be told, will reveal to us that grey is nearer than black to white; and taste may be our judge when we have hot, cold and no intermediate.
That we are accustomed to act upon these assumptions is obvious enough; but the following considerations may perhaps commend themselves:
White and yellow are entirely different from each other- a statement which applies to any colour whatsoever as compared with any other; they are accordingly contrary qualities. Their contrariety is independent of the presence of intermediates: between health and disease no intermediate intrudes, and yet they are contraries.
It may be urged that the products of a contrariety exhibit the greatest diversity. But "the greatest diversity" is clearly meaningless, unless we can point to lower degrees of diversity in the means. Thus, we cannot speak of "the greatest diversity" in reference to health and disease. This definition of contrariety is therefore inadmissible.
Suppose that we say "great diversity" instead of "the greatest": if "great" is equivalent to greater and implies a less, immediate contraries will again escape us; if, on the other hand, we mean strictly "great" and assume that every quality shows a great divergence from every other, we must not suppose that the divergence can be measured by a comparative.
Nonetheless, we must endeavour to find a meaning for the term "contrary." Can we accept the principle that when things have a certain similarity which is not generic nor in any sense due to admixture, but a similarity residing in their forms- if the term be permitted- they differ in degree but are not contraries; contraries being rather those things which have no specific identity? It would be necessary to stipulate that they belong to the same genus, Quality, in order to cover those immediate contraries which [apparently] have nothing conducing to similarity, inasmuch as there are no intermediates looking both ways, as it were, and having a mutual similarity to each other; some contraries are precluded by their isolation from similarity.
If these observations be sound, colours which have a common ground will not be contraries. But there will be nothing to prevent, not indeed every colour from being contrary to every other, but any one colour from being contrary to any other; and similarly with tastes. This will serve as a statement of the problem.
As for Degree [subsisting in Quality], it was given as our opinion that it exists in the objects participating in Quality, though whether it enters into qualities as such- into health and justice- was left open to question. If indeed these qualities possess an extension quite apart from their participants, we must actually ascribe to them degrees: but in truth they belong to a sphere where each entity is the whole and does not admit of degree.