"Nec eventus modo hoc docet, stultorum iste magister est, sed eadem ratio, quae fuit futuraque, donec res eaedem manebunt, immutabilis est."
Livy, History of Rome, Book 22
And it is not only the result that will instruct them, that teacher of fools, but reason itself, which was and will be unchanging, so long as the same fundamental conditions still hold.
"Let us then compose ourselves, and bear a firm and courageous heart. Let us feel what we really are,—sinners attempting great things, and succeeding at best only so far as to show that we do attempt them. Let us simply obey God's will, whatever may befall; whether it tend to elate us or to depress us, what is that to us? He can turn all things to our eternal good. He can bless and sanctify even our infirmities." J. H. Newman