A sage is not afraid of lack of knowledge: he is not afraid of hesitations, or hard work, but he is afraid of only one thing - to pretend to know the things which he does not know.
You should study more to understand that you know little.
— Michael De Montaigne
Never be ashamed to admit what you do not know.
— Arab Proverb
Put everything to the test, hold fast to that which is good.
— 1 Thessalonians 5:21
Real wisdom comes, not from knowing what is good and what should be done, but from knowing which is the better thing and which is the worse, and therefore, what should be done and what should be done later.
To be wise one must study both good and bad thoughts and acts, but one should study the bad first. You should first know what is not clever, what is not just, and what is not necessary to do.