pecunia non olet

money doesn't smell

Notes

According to Suetonius' De vita Caesarum, when Emperor Vespasian was challenged by his son Titus for taxing the public lavatories, the emperor held up a coin before his son and asked whether it smelled or simply said non olet ("it doesn't smell"). From this, the phrase was expanded to pecunia non olet, or rarely aes non olet ("copper doesn't smell").

Words