1824, A Treatise on Mental Derangement, Francis Willis (Junior).

For therapeutic purposes [Francis] Willis [senior, who treated King George III] fostered a sense of fear in his patients, ‘because', he was quoted as saying, 'fear provides the only grip that one can obtain on the mind of a maniac.' Willis acquired a reputation for gaining control over patients by catching their eye. One writer noted that he had an eye like Mars, to threaten or command... his numerous patients stood as much in awe of this formidable weapon, as of bars, chains or straight-waistcoats.