Thus, al-Armawī’s statement:

“Motion and rest are opposed either as contraries or as privation and possession. On either assumption, their essential natures must differ, rather than be alike,”

is correct. But his opponent’s statement:

“If the difference is due to an incidental attribute, as between a black object and a white object, their essential natures need not differ, since the essential nature of a black object is of the same kind as that of a white object,”

is false. For a black object and a white object belong to the category of independently subsisting bodies, not that of attributes and accidents.

Moreover, a black object and a white object are opposed neither as contraries nor as privation and possession, so they do not fall within this category—unless, of course, what is meant is that the space occupied by the black object cannot be occupied by the white object. In that case, the opposition between the white object and the black object is like that between two black objects or two white objects.

Furthermore, one may say: Does the difference between a black object and a white object mean a difference between the individual entities themselves, disregarding blackness and whiteness, or a difference between them subject to the conditions of blackness and whiteness? If the former is intended, there is no difference between the underlying entities when the two colours are disregarded, for the body that is black may be the very same body that is white. If, however, what is intended is their difference subject to the condition of differing colours, then their difference is like that between blackness and whiteness. For a thing considered subject to the condition of blackness differs from a thing considered subject to the condition of whiteness.

It is not permissible to say that the two underlying entities are identical in nature except when considered in abstraction