Caligula, the third emperor of Rome, figures today as the classic template for a Mad King. To a man, antique historians—Seneca, Tacitus, Suetonius, Cassius Dio, the whole bunch—reported that he was “mentally ill,” “sick,” and “insane.” Their list of his abominations is long and includes bloodthirstiness; incest; delusions of godhood; transvestism (a consequence of his appearances at state functions as Diana); the use of the legions to make war on Olympus (specifically, Neptune); the forcible prostitution of highborn Roman matrons; and the appointment of a favorite racehorse, Incitatus, to the Senate.

In the introduction to his new biography, Caligula, the Swiss classicist Aloys Winterling ranges himself in the camp of contemporary historians—by no means a tiny minority—who claim that the third emperor was not, in fact, mad. The argument is based both on the unreliability of...

 
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