The Heroides is a collection of 21 poems in elegiac couplets. The Heroides take the form of letters addressed by famous mythological characters to their partners expressing their emotions at being separated from them, pleas for their return, and allusions to their future actions within their own mythology.The first 14 letters are thought to comprise the first published collection and are written by the heroines Penelope, Phyllis, Briseis, Phaedra, Oenone, Hypsipyle, Dido, Hermione, Deianeira, Ariadne, Canace, Medea, Laodamia, and Hypermestra to their absent male lovers. Letter 15 is from the historical Sappho to Phaon. The final letters (16–21) are paired compositions comprising a letter to a lover and a reply. Paris and Helen, Hero and Leander, and Acontius and Cydippe are the addressees of the paired letters. These are considered a later addition to the corpus because they are never mentioned by Ovid and may or may not be spurious.