you can't make a silk purse of a sow's ear
词源说明
From make a silk purse of a sow's ear, with the common perception of swine as unrefined, dirty, or base creatures.
释义（英文）
谚语 Proverb
- It is not possible to produce something refined, admirable, or valuable from something which is unrefined, unpleasant, or of little or no value.