The only limits that exist are the ones you place on yourself.

译文：高贵的人虽然自以为尊贵，但在我看来却如尘埃;低贱的人虽然自以为卑微，但在我看来却重如千钧。

Virtue is more to be feared than vice， because its excesses are not subject to the regulation of conscience.

我不是因为快乐而唱歌；我因为唱歌而快乐。