The arts of speech are rhetoric and poetry. Rhetoric is the art of transacting a serious business of the understanding as if it were a free play of the imagination; poetry that of conducting a free play of the imagination as if it were a serious business of the understanding.
But the virtues we get by first exercising them, as also happens in the case of the arts as well. For the things we have to learn before we can do them, we learn by doing them, e.g. men become builders by building and lyre players by playing the lyre; so too we become just by doing just acts, temperate by doing temperate acts, brave by doing brave acts.
The supreme question about a work of art is out of how deep a life does it spring. Paintings of Moreau are paintings of ideas. The deepest poetry of Shelley, the words of Hamlet bring our mind into contact with the eternal wisdom; Plato's world of ideas. All the rest is the speculation of schoolboys for schoolboys.
If we examine a work of ordinary art, by means of a powerful microscope, all traces of resemblance to nature will disappear - but the closest scrutiny of the photogenic drawing discloses only a more absolute truth, a more perfect identity of aspect with the thing represented.