Ver. 68. _First follow nature, &c._] The critic observing the directions before given, and now finding himself qualified for his office, is shown next how to exercise it. And as he was to attend to nature for a call, so he is first and principally to follow nature when called. And here again in this, as in the foregoing precept, our poet, from ver. 67 to 88, shows both the fitness and necessity of it. I. Its fitness. 1. Because nature is the source of poetic art, this art being only a representation of nature, who is its great exemplar and original. 2. Because nature is the end of art, the design of poetry being to convey the knowledge of nature in the most agreeable manner. 3. Because nature is the test of art, as she is unerring, constant, and still the same. Hence the poet observes, that as nature is the source, she conveys life to art; as she is the end, she conveys force to it, for the force of any thing arises from its being directed to its end; and as she is the test, she conveys beauty to it, for everything acquires beauty by its being reduced to its true standard. Such is the sense of these two important lines, Life, force, and beauty must to all impart, At once the source, and end, and test of art. II. The necessity of the precept is seen from hence. The two constituent qualities of a composition, as such, are art and wit; but neither of these attains perfection, till the first be hid, and the other judiciously restrained. This only happens when nature is exactly followed; for then art never makes a parade; nor can wit commit an extravagance. Art, while it adheres to nature, and has so large a fund in the resources which nature supplies, disposes every thing with so much ease and simplicity, that we see nothing but those natural images it works with, while itself stands unobserved behind; but when art leaves nature, misled either by the bold sallies of fancy, or the quaint oddness of fashion, she is then obliged at every step to come forward, in a painful or pompous ostentation, in order to cover, to soften, or to regulate the shocking disproportion of unnatural images. In the first case, our poet compares art to the soul within, informing a beauteous body; but in the last, we are bid to consider it but as a mere outward garb, fitted only to hide the defects of a misshapen one. As to wit, it might perhaps be imagined that this needed only judgment to govern it; but, as he well observes, wit and judgment often are at strife, Though meant each other's aid, like man and wife. They want therefore some friendly mediator; and this mediator is nature: and in attending to nature, judgment will learn where he should comply with the charms of wit; and wit how she ought to obey the sage directions of judgment.