One other matter is suggested by the words _national usage_. A nation is composed of all sorts and conditions of men. Each class, each trade and profession, has its own pet expressions and contractions. Good usage does not recognize these. The dialect of the college, or the ball-ground, or the counting-room, or the law-courts, is racy enough and proper enough in its place; but it has no place in standard English. A student may _flunk_, but only in school. A book of accounts can be _posted_, but not a man.
Again, our words must not be so old-fashioned or obsolete that they are unintelligible. They must be _present_. _Let_ once meant “to hinder.” Naturally no one would use it in this sense to-day.
Many words that are both national and present are not permitted, since they are not _reputable_. They are used, but wrongly so; used by the careless and the uneducated. A great number of such expressions are perfectly well understood wherever English is spoken, but if one employs them one will be set down as careless or ignorant; for example, _ain’t_ is intelligible to all, but its use is known to be a mark of vulgarity; such a word is called a _vulgarism_. Most slang consists of vulgarisms, though some slang finally becomes reputable English. Reputable words are those employed by the best writers. By _best_ is meant writers who have literary distinction, and who know and regard the structure and history of English literary words. In this day, when everybody scribbles and prints, there are countless writers whose usage is not really reputable. The newspapers, though they have done much to free modern English from pedantry, are not usually reputable in usage. The English of very many novelists is in bad repute. Even certain writers of eminence, such as Dickens and Thomas Hughes, are guilty of using unreputable words and senses of words. Such essayists as Matthew Arnold and John Fiske; such writers of fiction as Thackeray, Hawthorne, Stevenson, and Henry James; such historians as Green and Parkman—these men are in general safe models in matters of usage.
To sum up, then; if we would be understood, and would be reckoned as educated persons, we must use words that are reputable, national, and present. _Good usage is the employment of such words and, senses of words as the body of reputable writers sanction by their own practice to-day._ Notice that _the body_ of reputable writers is specified. No one author makes good use, any more than one swallow makes a summer. When a critic wishes to prove by authority that a given expression is English, he must be able to quote it from many authors.