Nor must we forget that our own ideas of propriety are constantly changing. Take the single instance of the use, in literature, of words regarded as profane or vulgar. Most of us can recollect a time when our acquaintances were likely to be shocked by the occurrence in a book of the expletive “damn”--that is, if it were spelled out. It was generally held to be unobjectionable, or at least less objectionable, if the second and third letters were replaced by a dash. Evidently this is the purest convention. This and worse words appear now, not without shocking some persons, to be sure, but certainly without shocking many of those who formerly would not have tolerated them. On the other hand, it would not be difficult to instance words formerly common in good literature whose use would now cause something of a sensation. There are also good people who will read unmoved surprising words and expressions when put into the mouth of a cowboy or a Klondike miner, but whose gorge would rise if the same words were employed by a writer _in propria persona_. What is true of words is true also of subjects. That which could not be touched upon yesterday is discussed freely to-day, and _vice-versa_. No way of dealing with the situation will fail to offend some one, and the only approximation to satisfaction will be gained by the use of common sense applied to each case as it comes up. Indecency, of course, is not the only offense against beauty that a book may commit. It may be trashy, that is, its subject matter or the manner in which it is treated may be trivial and worthless. The dust of the street is neither beautiful nor valuable, although it may contain nothing injurious to health or repulsive to the senses. The diction of the book may offend against beauty and order by its incorrectness; its paper, its typography, its binding, its illustrations may all be offensive to the eye. These last are mere matters of outward show, to be sure; it may be necessary to disregard them. They are usually reasons for excluding an edition rather than a book, though sometimes the only obtainable edition offends in so many of these ways as to make it unpurchasable, even if otherwise desirable. So far as they militate against the usefulness of the book rather than its beauty, as in the case of the badly sewed binding or paper that is comely but flimsy, they fall under the head of badness rather than that of ugliness--they are offenses against the Good and not against the Beautiful. Such material grounds for rejection, however, are not peculiar to books, and I do not dwell on them here. Ugliness that consists in mere triviality or in incorrectness of diction has this in common with impropriety--it is arbitrary and conventional. With regard to language, this is obvious. The fact that a certain combination of sounds means one thing in France and another in England and is quite unintelligible perhaps in Spain, is