But in process of time, and in ages of ignorance, the clerk began to invade the power and assume the dignity of his master. The laws of writing were no longer founded on the practice of the author, but on the dictates of the critic. The clerk became the legislator, and those very peremptorily gave laws whose business it was, at first, only to transcribe them. Hence arose an obvious, and perhaps an unavoidable error; for these critics being men of shallow capacities, very easily mistook mere form for substance. They acted as a judge would, who should adhere to the lifeless letter of law, and reject the spirit. Little circumstances, which were perhaps accidental in a great author, were by these critics considered to constitute his chief merit, and transmitted as essentials to be observed by all his successors. To these encroachments, time and ignorance, the two great supporters of imposture, gave authority; and thus many rules for good writing have been established, which have not the least foundation in truth or nature; and which commonly serve for no other purpose than to curb and restrain genius, in the same manner as it would have restrained the dancing-master, had the many excellent treatises on that art laid it down as an essential rule that every man must dance in chains. To avoid, therefore, all imputation of laying down a rule for posterity, founded only on the authority of _ipse dixit_--for which, to say the truth, we have not the profoundest veneration--we shall here waive the privilege above contended for, and proceed to lay before the reader the reasons which have induced us to intersperse these several digressive essays in the course of this work. And here we shall of necessity be led to open a new vein of knowledge, which if it hath been discovered, hath not, to our remembrance, been wrought on by any antient or modern writer. This vein is no other than that of contrast, which runs through all the works of the creation, and may probably have a large share in constituting in us the idea of all beauty, as well natural as artificial: for what demonstrates the beauty and excellence of anything but its reverse? Thus the beauty of day, and that of summer, is set off by the horrors of night and winter. And, I believe, if it was possible for a man to have seen only the two former, he would have a very imperfect idea of their beauty. But to avoid too serious an air; can it be doubted, but that the finest woman in the world would lose all benefit of her charms in the eye of a man who had never seen one of another cast? The ladies themselves seem so sensible of this, that they are all industrious to procure foils: nay, they will become foils to themselves; for I have observed (at Bath particularly) that they endeavour to appear as ugly as possible in the morning, in order to set off that beauty which they intend to show you in the evening.