Learning carries within itself certain dangers because out of necessity one has to learn from one's enemies.
The opposition is indispensable. A good statesman, like any other sensible human being, always learns more from his opponents than from his fervent supporters.
The only teacher that's worth anything to you is your enemy.
There are people who pay attention to the weaknesses of their friends; that is to no avail. I have always closely watched and profited from the strengths of my adversaries.
You can learn from anyone even your enemy.
It's right to learn, even from the enemy.
Fas est ab hoste doceri. One should learn even from one's enemies.
It is lawful to be taught by an enemy. Fas est ab hoste doceri.
Men of sense often learn from their enemies. It is from their foes, not their friends, that cities learn the lesson of building high walls and ships of war.
It is from our enemies that we often gain excellent maxims, and are frequently surprised into reason by their mistakes.
