The man who does not restrain wantonness, allies himself with beasts.
You can have no dominion greater or less than that over yourself.
He who thinks little, errs much.
It is easier to contend with evil at the first than at the last.
No counsel is more loyal than that given on ships which are in peril: He may expect loss who acts on the advice of an inexperienced youth.
Taken from The Notebooks of Leonardo da Vinci edited by Jean Paul Richter, 1880.