Anybody who'd do something that convinces all his friends he's nuts must be nuts.
"The Foreign Hand Tie"
Gordon Randall Garrett
"We find the prisoner guilty, my Lords," said Repton; "but we recommend him to mercy, as his manner on this occasion convinces us it is a first offence."
"The Martins Of Cro' Martin, Vol. II (of II)"
Charles James Lever
Do you believe I am your dream come true with the same matter-of-fact belief which convinces you that there is a ferry in the river?
"The Mystery of the Locks"
Edgar Watson Howe