If gold ruste, what shal iren do?
Modern English:
If gold rust, what must iron do?

– Geoffrey Chaucer

The Canterbury Tales, General Prologue. The words of the good and devout Parson. Chaucer uses metaphors here to explain the poisonous nature of church corruption. Gold is the church figures, iron the average person, and iron corruptness. Chaucer is suggesting that if the church shepherds are corrupt, the sheep will surely follow and be likewise.