Further, how can States constitute a single genus, when there is such manifold diversity among them? How can we group together three yards long” and “white” – QUANTITY AND QUALITY respectively? Or again Time and Place? How can “yesterday,” “last year,” “in the Lyceum,” “in the Academy,” be States at all? How can Time be in any sense a State? Neither is Time a State nor the events in Time, neither the objects in Space nor Space itself. Enneads VI,1,30
Why is Quality, again, not included among the Primaries? Because like Quantity it is a posterior, subsequent to Substance. Primary Substance must necessarily contain QUANTITY AND QUALITY as its consequents; it cannot owe its subsistence to them, or require them for its completion: that would make it posterior to Quality and Quantity. Enneads VI,2,14
As we survey this Magnitude with the beauty of Being within it and the glory and light around it, all contained in Intellect, we see, simultaneously, Quality already in bloom, and along with the continuity of its Act we catch a glimpse of Magnitude at Rest. Then, with one, two and three in Intellect, Magnitude appears as of three dimensions, with Quantity entire. Quantity thus given and Quality, both merging into one and, we may almost say, becoming one, there is at once shape. Difference slips in to divide both QUANTITY AND QUALITY, and so we have variations in shape and differences of Quality. Identity, coming in with Difference, creates equality, Difference meanwhile introducing into Quantity inequality, whether in number or in magnitude: thus are produced circles and squares, and irregular figures, with number like and unlike, odd and even. Enneads VI,2,21
But suppose similarity to be identical in both genera; QUANTITY AND QUALITY must then be expected to reveal other properties held in common. Enneads VI,3,15