E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The living double of another, as the brothers Antipholus and brothers Dromio in the Comedy of Errors, and the Corsican brothers in the drama so called. Sosia is a servant of Amphitryon, in Plautuss comedy so called. It is Mercury who assumes the double of Sosia, till Sosia doubts his own identity. Both Dryden and Molière have adapted this play to the modern stage, but the Comedy of Errors is based on another drama of the same author, called the Menæchmi. (See AMPHITRYON.)