"Can't you?" the queen said in a pitying tone. "Try again, draw a long breath, and shut your eyes."
Alice laughed: "There's no use trying," she said; "one can't believe impossible things."
"I daresay you haven't had much practice," said the Queen. "When I was younger, I always did it for half an hour a day. Why, sometimes I've believed as many as six impossible things before breakfast."
(From 'Through The Looking-Glass' by Lewis Carroll)