E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Lunatics.
Moon-struck persons. The Romans believed that the mind was affected by the moon, and that “lunatics” were more and more frenzied as the moon increased to its full. (See AVERTIN.)
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“The various mental derangements … which have been attributed to the influence of the moon, have given to this day the name lunatics to persons suffering from serious mental disorders.”—Crozier: Popular Errors, chap. iv. p. 53.
