Odysseus, sitting full in the firelight, suddenly
swerved round to the dark, gripped by a misgiving –
soon as she touched him she might spot the scar!
The truth would come out.
– Homer
The Odyssey, Book 19, lines 440-446. When Eurycleia comes with a basin and water to wash Odysseus’ feet, he is worried that she might see through his disguise. He fears that she might recognize him from a childhood scar he has on his thigh.