Si jeunesse savait, si vieillesse pouvait = If only the young had experience and the old strength; If things were to be done twice, all would be wise.

Ce que poulain prend en jeunesse, il le continue en vieillesse =

“'Tis education forms the common mind. Just as the twig is bent the tree's inclined.” [POPE, Moral Essays, i. 149.]

Youth and white paper take any impression.

[Also: Vieil arbre mal aisé à redresser. Compare the English, “Old dogs are hard to train.” (See Jeune.)

“Train up a child in the way he should go, and when he is old he will not depart from it.”--PROVERBS xxii. 6.]

Il faut que jeunesse se passe = Boys will be boys.