pour exprimer les regrets

there must be a million things in life we regret, wish never happened or wish we could've changed. then again, it's necessary to remember that today exists by virtue (or by fault) of days and events gone by. If it's a good thing that we have the wisdom (albeit of hindsight), then this goodness must be the value of those mistakes made.

so let's value our mistakes well, for to learn, we must first learn how to fail.

now, let's try that in french. seriously, it's pretty clear that from "it's necessary...":
mais, il faut souvenir que le présent n'existe qu'à cause du passé.
okay skip skip too chim heh

donc, vaut bien des erreurs; pour qu'on sache comment réussir, il faut savoir comment échouer.