Plotinos: Complete Works, v. 1 In Chronological Order,...

The first principles, therefore, are existence and intelligence, identity and difference, movement and rest.230 Rest is the condition of identity; movement is the condition of thought, since the latter presupposes the differences of the thinking subject and of the object thought, and because it is silent if reduced to unity. The elements of thought (subject and object) must thus stand in the relation of differences, but also in that of unity, because they form a consubstantial unity, and because there is a common element in all that is derived therefrom. Besides, here difference is nothing else than distinction. The plurality formed by elements of thought constitutes quantity and number;231 and the characteristic of every element, quality.232 From these first principles (the categories, that are the genera of being) all things are derived.