Every sense exercises itself upon its proper object, and exercises itself completely when it is in good condition and the object is the noblest of those that fall within its scope (for the complete exercise of a faculty seems to mean this; and we may assume that it makes no difference whether we speak of the sense, or of the sensitive subject as exercising itself): of each sense, then, we may say that the exercise is best when on the one side you have the finest condition, and on the other the highest of the objects that fall within the scope of this faculty.

But this exercise of the faculty will be not only the most complete, but also the pleasantest: for the exercise of every sense is attended with pleasure, and so is the exercise of reason and the speculative faculty; and it is pleasantest when it is most complete, and it is most complete when the faculty is well-trained and the object is the best of those that fall under this faculty.