The following is an excerpt from Through the Looking-Glass and What Alice Found There by Lewis Carroll. It is a conversation between Alice and the White Queen:
“I’m seven and a half exactly.”
“You needn’t say ‘exactually,'” the Queen remarked: “I can believe it without that. Now I’ll give you something to believe. I’m just one hundred and one, five months and a day.”
“I can’t believe that!” said Alice.
“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 your age, I always did it for half-an-hour a day. Why, sometimes I’ve believed as many as six impossible things before breakfast.
The White Queen is of course mad. She can believe anything because she chooses her beliefs.
Sin is a sort of dark madness through which we often delude ourselves. Contrariwise, the truth is a rock. We receive truth as a gift, not a choice. (James 1:17-18).