Those men who will give any certain direction for the writing of any tongue, or for anything else that concerns a tongue, must take some period in its history, or else their rules will prove inapplicable. For every tongue has a certain ascent from the lowest to the highest point, and a descent again from the highest to the lowest; and as in the ascent it has not reached a secure position, because it is not thoroughly reduced to art, so in the descent it comes to be not worth noting, because it gets rude again, and in a manner withered. Hence it comes that the age of Demosthenes is the prince of Greece, as that of Cicero is the flower of Rome, and if the languages of these countries had not been committed to the security of books, they would have been of little worth; nay, they would have been forgotten altogether, long before our day, as the spoken tongues of those nations, changing continually since the periods named, are now quite altered, or at least are nothing like what they were in their prime, though still blooming in another form. So that books give life where bodies bring only death. Consider the Greek and Latin writers before the ages of those men, and by comparing them with these, you will see the difference that I spoke of, the earlier being too rude to be brought under rule, and the later departing from established rules and yielding to change. This period of full development, with the ascent to it and the decline leading to decay, shows us that everything belonging to man is subject to change, the language changing also, but never dying out. It must needs be therefore that there is something of the nature of a soul in every spoken tongue that feeds this change even with perceptible means. For if any tongue be fixed, and free from movement, it is enshrined in books, not subject to ordinary use, but made immortal by the register of memory.
This secret mystery, or rather quickening spirit, that dwells in every spoken tongue, and therefore in our own, I call “prerogative,” because when sound has done his best, when reason has said his best, and when custom has carried into effect what is best in both, this prerogative will resist any of them, and take exception to all their rules, however general and certain. It thus makes way for a new change, which will follow at some stage of the language, if the writer’s period be chosen at the best. I cannot compare this customary prerogative in speech to anything better than to those who devise new garments, and are left by law to liberty of device. Hence it comes in the matter of apparel, that we do not remain like ourselves for any length of time, though what is most seemly, like a rule of art, pleases the wisest people best. From this same liberty of speech to carve out a way for itself, come the exceptions to our general rules. Hence it comes that _enough_, _bough_, _tough_, and such other primitives are so strangely written, and more strangely sounded. In this way prerogative seems to be like quicksilver, ever stirring and never settled, though the general custom always offers itself to be ordered by rule, as a close friend to reason. This stirring quintessence, leading to change in a thing that is naturally changeable and not blameworthy for changing, some not very well-advised people consider as an error, and a private misuse, contrary to custom, because it seems to be a very imperious controller, but in this they are deceived. For indeed, though this prerogative, by opposition in particular cases, checks general conclusions, yet that opposition came not from individual men; it is a private thing itself, and the very life-blood which preserves tongues in their best natural form, from the first time that they grew to be of any account till they come to decay, and begin a new period, different from the old, though excellent in its kind, which in its turn must give way to another when the time is ripe.