text: Therefore the power and the greatness of virtue cannot rise to greater heights, because increase is denied to that which is superlatively great. You will find nothing straighter than the straight, nothing truer than the truth, and nothing more temperate than that which is temperate. Every virtue is
  limitless; for limits depend upon definite measurements. Constancy cannot advance further, any more than fidelity, or truthfulness, or loyalty. What can be added to that which is perfect? Nothing otherwise that was not perfect to which something has been added. Nor can anything be added to virtue, either, for if anything can be added thereto, it must have contained a defect. Honour, also, permits of no addition; for it is honourable because of the very qualities which I have mentioned. What then? Do you think that propriety, justice, lawfulness, do not also belong to the same type, and that they are kept within fixed limits? The ability to increase is proof that a thing is still imperfect.