If you put a silk dress on a goat he is a goat still.
More Traditional Proverbs:
The good seaman weathers the storm he cannot avoid, and avoids the storm he cannot weather
Traditional
You can't teach an old dog new tricks.
Traditional
If I wanted an easy care garden, I would have planted weeds.
Traditional
Money lent to a friend must be recovered from an enemy
Traditional
Altruism is the mark of a superior being.
Traditional