You cannot forge a good sword from bad iron.
More Turkish Proverbs:
The wise man says what he knows; the fool doesn't know what he is saying.
Turkish
The baker's child goes hungry.
Turkish
Even though you know a thousand things, ask the man who knows one.
Turkish
The rose comes from the thorns that were born of roses.
Turkish
Tell a lie on Saturday and you will be ashamed on Sunday.
Turkish