The master was an old Turtle—we used to call him Tortoise—' Why did you call him Tortoise, if he wasn't one?' Alice asked. We called him Tortoise because he taught us,' said the Mock Turtle angrily; 'really you are very dull!' You ought to be ashamed of yourself for asking such a simple question,' added the Gryphon; and then they both sat silent and looked at poor Alice, who felt ready to sink into the earth.

The Lewis Carroll Book (ed. 1936)