The text ofTwelfth Night, as printed in the Folio of 1623, is unusually accurate. There is no earlier edition.

John Manningham of the Middle Temple sawTwelfth Nightperformed on February 2, 1602. “At our feast,” he notes in his Diary,“wee had a play calledTwelue Night, or What You Will, much like theCommedy of Errores, orMenechmiin Plautus, but most like and neere to that in Italian calledInganni.” He commends particularly the trick played on Malvolio, which he calls “a good practise” (i.e., a clever device). “Twelue” is an old form of the ordinal; the Folio spells it “twelfe.” Manningham’s record fixes one limit for the date of composition. Obviously he had never seen the play before, but that does not prove that it was absolutely new. The title tempts inference that the first production was on the twelfth night (Epiphany) immediately preceding, that is, on January 6, 1602. Anyhow, 1601 (or 1600 at the earliest) may safely be accepted as the date of composition. No circumstantial evidence conflicts with this date. “The new map with the augmentation of the Indies” (3.2.85) was doubtless that of Emerie Molyneux (ca.1599). The “pension of thousands to be paid from the Sophy” (2.5.197), that is, the Shah of Persia, may allude to Sir Robert Shirley’s return from that country in 1599, with rich gifts from the Shah.

The source for the main plot ofTwelfth Nightis Barnabe Riche’s taleOf Apolonius and Silla,the second “historie” inRiche his Farewell to Militarie Profession(1581). Shakespeare’s Viola is Riche’s Silla. Viola’s romance begins with a shipwreck, which separated her from her brother Sebastian and cast her up on Duke Orsino’s Illyrian coast. Silla is likewise shipwrecked, but the first chapter of her love story is staged in Cyprus, at her father’s court, where she fell in love with Duke Apolonius, her father’s guest, and sought to win him, but in vain. Apolonius returns to his home in Constantinople and Silla determines to follow him. The shipwreck is the end of her journey. Her brother Silvio is not with her, but she is accompanied by a trusty servant (Pedro) who passes for her brother during the voyage. The shipwreck is fortunate, for, though it separates her from Pedro, it saves her from the violent attentions of the shipmaster. She is washed ashore on a chest that contains good store of coin and sundry suits of the captain’s clothes. Under the name of her brother Silvio (Shakespeare’s Sebastian) she takes service with Apolonius, who of course does not recognize her. He, in the meantime, has succumbed to the charms of an obdurate young widow, Julina (Shakespeare’s Olivia), and he employs Silla as his messenger with letters and gifts. Julina falls in love with her while she is pleading her master’s cause and interrupts: “Silvio, it is enough that you have said for your maister; from henceforthe, either speake for your self, or saie nothyng at all.” Shakespeare’s Olivia is less blunt, but equally frank . . .