For the purposes of correspondence, one may and must throw himself back into the immediate past and assume the mood that was his when he wrote and in which alone a reply can find him. But there is a limit to this power, which is soon reached. Not many letters will keep sweet more than two days. A little indulgence may, perhaps, be shown toward persons who are a week or a fortnight from us by the post, since otherwise we could never converse together. But even they should reply to only the weightier matters suggested, since what they say will probably be stale before it reaches the eyes for which it was written. For the like reasons, I hold a Californian or European correspondence to be an impossibility. As for him whose want of politeness fixes a gulf, a week broad, between himself and his correspondent, there is no excuse. As one reads a letter, an answer to whatever worth answering may be in it leaps to the lips; to give it utterance that moment is the only natural, courteous, and truthful course. Ten days hence, the reply, which now comes of its own accord, cannot be found; what might have been a source of pleasure to two persons will have become a piece of thankless drudgery. In vain the conscientious correspondent, at the appointed time, takes the letter which she would answer out of the compartment of her portfolio, whereon stationers, cunningly humoring a popular weakness, have gilded,--"UNANSWERED LETTERS." In vain she cons it with care, comments upon every observation in it, answers all its questions one by one, and propounds a series of her own, as a basis for the next epistle. Everything has been done decently and in order; but the laboriously-produced letter is a letter which killeth, and contains no infusion of the spirit that giveth life. This is not the writer's fault. It is and must be all but impossible, after a lapse of time, to reproduce the natural reply to a remark, or to concoct one that shall be vital and satisfactory to the other party. Lovers, of all persons, it would seem, might with least danger postpone answering each other's missives, since their common topic of interest is always with them, and the _billet-doux_, after having been carried in the bosom a week, is as fresh as when taken from the post-office. What need for "sweet sixteen" to consume the very night of its reception in essaying a reply, which she might have written next week as well, since next week they two will stand in substantially the same relations to one another as now? "Sweet sixteen" smiles at such coldblooded logic. "To you others," thinks she to herself, "all sunsets may be alike; but in our horizon are constant changes, delicate tones of color, each 'Shade so finely touched love's sense must seize it.' The mood into which Walter's note put me may never return again. Now it is correspondent to the mood in which he wrote; now or never must I reply. In this way alone can we keep up a correspondence between our natures."