Everything is destroyed by ...

Everything is destroyed by its own particular vice: the destructive power resides within. Rust destroys iron, moths destroy clothes, the worm eats away the wood; but greatest of all evils is envy, impious habitant of corrupt souls, which ever was, is, and shall be a consuming disease.
 Menander

Quotes from the same author

Know thyself means this, that you get acquainted with what you know, and what you can do.
 Menander
He who labors diligently need never despair for all things are accomplished by diligence and labor.
 Menander
All men have one refuge, a good friend, with whom you can weep and know that he does not smile.
 Menander