Michel de Montaigne

“ But forasmuch as the strength or weakness of a fortress is always
measured by the estimate and counterpoise of the forces that attack it
--for a man might reasonably enough despise two culverins, that would be
a madman to abide a battery of thirty pieces of cannon--where also the
greatness of the prince who is master of the field, his reputation, and
the respect that is due unto him, are also put into the balance, there is
danger that the balance be pressed too much in that direction. ”

“ Valour has its bounds as well as other virtues, which, once transgressed,
the next step is into the territories of vice; so that by having too
large a proportion of this heroic virtue, unless a man be very perfect in
its limits, which upon the confines are very hard to discern, he may very
easily unawares run into temerity, obstinacy, and folly. ”