Ver. 216. _Drink deep, &c._] Nature and learning are the pole-stars of all true criticism: but pride obstructs the view of nature; and a smattering of letters makes us insensible of our ignorance. To avoid this ridiculous situation, the poet, from ver. 214 to 233, advises, either to drink deep, or not to drink at all; for the least sip at this fountain is enough to make a bad critic, while even a moderate draught can never make a good one. And yet the labours and difficulties of drinking deep are so great, that a young author, "fired with ideas of fair Italy," and ambitious to snatch a palm from Rome, here engages in an undertaking like that of Hannibal: finely illustrated by the similitude of an inexperienced traveller penetrating through the Alps. Ver. 233. _A perfect judge, &c._] The third cause of wrong judgment is a narrow capacity; the natural cause of the foregoing defect, acquiescence in superficial learning. This bounded capacity our author shows, from ver. 232 to 384, betrays itself two ways: in its judgment both of the matter, and the manner of the work criticised. Of the matter, in judging by parts, or in having one favourite part to a neglect of all the rest. Of the manner, in confining men's regard only to conceit, or language, or numbers. This is our poet's order, and we shall follow him as it leads us, only just observing one general beauty which runs through this part of the poem; it is,--that under each of these heads of wrong judgment, he has intermixed excellent precepts for the right. We shall take notice of them as they occur. He exposes the folly of judging by parts very artfully, not by a direct description of that sort of critic, but of his opposite, a perfect judge, &c. Nor is the elegance of this conversion less than the art; for as, in poetical _style_, one word or figure is still put for another, in order to catch new lights from distant images, and reflect them back upon the subject in hand, so in poetical _matter_ one person or description may be commodiously employed for another, with the same advantage of representation. It is observable that our author makes it almost the necessary consequence of judging by parts, to find fault: and this not without much discernment: for the several parts of a complete whole, when seen only singly, and known only independently, must always have the appearance of irregularity,--often of deformity; because the poet's design being to create a resultive beauty from the artful assemblage of several various parts into one natural whole, those parts must be fashioned with regard to their mutual relations in the stations they occupy in that whole, from whence the beauty required is to arise; but that regard will occasion so unreducible a form in each part, when considered singly, as to present a very mis-shapen form.