If it is thus, then, that every art does its work well by looking to the intermediate and judging its works by this standard (so that we often say of good works of the art that it is not possible either to take away or to add anything, implying that excess and defect destroy the goodness of works of art, while the mean preserves it; and good artists, as we say, look to this in their work), and if, further, excellence is more exact and better than any art, as nature also is, then it must have the quality of aiming at the intermediate.