There are many, I know, who think there is no necessity for instruction at all with regard to this business, any more than there is for walking, seeing, or eating, and that it is the easiest thing in the world for a man to write history if he can but say what comes uppermost. But you, my friend, are convinced that it is no such easy matter, nor should it be negligently and carelessly performed; but that, on the other hand, if there be anything in the whole circle of literature that requires more than ordinary care and attention, it is undoubtedly this. At least, if a man would wish, as Thucydides says, to labour for posterity. I very well know that I cannot attack so many without rendering myself obnoxious to some, especially those whose histories are already finished and made public; even if what I say should be approved by them, it would be madness to expect that they should retract anything or alter that which had been once established and, as it were, laid up in royal repositories. It may not be amiss, however, to give them these instructions, that in case of another war, the Getae against the Gauls, or the Indians, perhaps, against the barbarians (for with regard to ourselves there is no danger, our enemies being all subdued), by applying these rules if they like them, they may know better how to write for the future. If they do not choose this, they may even go on by their old measure; the physician will not break his heart if all the people of Abdera follow their own inclination and continue to act the Andromeda. {23} Criticism is twofold: that which teaches us what we are to choose, and that which teaches us what to avoid. We will begin with the last, and consider what those faults are which a writer of history should be free from; next, what it is that will lead him into the right path, how he should begin, what order and method he should observe, what he should pass over in silence, and what he should dwell upon, how things may be best illustrated and connected. Of these, and such as these, we will speak hereafter; in the meantime let us point out the faults which bad writers are most generally guilty of, the blunders which they commit in language, composition, and sentiment, with many other marks of ignorance, which it would be tedious to enumerate, and belong not to our present argument. The principal faults, as I observed to you, are in the language and composition.