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