As his only source for As You Like It, Shakespeare used Rosalynde: Euphues Golden Legacie, a novel written by Thomas Lodge, published in 1590. An introductory remark in Loge’s text is “If you like it, so”, and this may account for Shakespeare’s choice of title. Rosalynde is a pastoral romance, itself based on an earlier poem, The Coke’s Tale of Gamelyn, and Shakespeare used the characters of Rosalynde, Celia, Phebe, Corin, and Silvius, inventing the others characters of Touchstone, Jaques, Amiens, Audrey, and Le Beau to facilitate a parody of the traditional and conventional pastoral romance. The pastoral genre, full of fanciful country descriptions, is Greek in origin, beginning with the Idylls of Theocritus, but was called upon by writers throughout the centuries. Virgil employed the pastoral in his Eclogues, and Longus in his Daphnis and Chloe. The pastoral was not popular in medieval England, but it flourished during the Renaissance, with Petrarch, Cervantes, and Sidney. Sidney’s Arcadia, which Shakespeare used as a minor source for Pericles, is probably the best known pastoral romance.
S. C. Burchell points out the similarities between the texts of Shakespeare and Lodge in his Yale edition of the play:
It is obvious that As You Like It owes much to Lodge’s novel, but Shakespeare has made some significant changes and additions. He has focused the action most clearly on the Forest of Arden passages, cutting out a great deal of the introductory matter, particularly the long section on Rosader’s quarrel with his wicked brother, which he compressed to one brief interview. He also concentrated upon the romance of Rosalynde and Rosader, and, unlike Lodge, gave merely a brief account of Saladyne’s love for Alinda. But changes of this sort are obviously necessitated by the transition from a narrative to a dramatic form and reflect little of Shakespeare’s originality. (Burchell, 119)