“The Countess of Pembroke's Arcadia” by Sir Philip Sidney:

Arcadia is ruled by Duke Basilius, who wants to know about his future and seeks insight from an Oracle. He is told that his daughter Pamela will be stolen from him, his younger daughter Philoclea will become involved in an unsuitable love affair, and his wife Gynecia will become adulterous. Shocked by this, he leaves Arcadia and brings his daughters and wife with him. Meanwhile, two young princes arrive in Arcadia, Musidorous and Pyrocles, and Pyrocles comes across a picture of Philoclea. He swears he’s in love with her and needs to meet her. He decides that he will disguise himself as a heroic woman, “Zelmane” and travel to where the princesses are living, and Musidorous travels along with him. Basilius sees Pyrocles in his disguise as “Zelmane” and falls in love with him, meanwhile Musidorous comes up disguised and falls in love with Pamela. Later, Gynecia discovers Pyrocles real identity and also falls in love with him. Back in Arcadia, shepherds meet up to sing poetic songs and dance to entertain. These songs are about Gods and human love and passions, which only intensifies these new relationships, and everything becomes more and more tangled.

Traces of this story can be found in some of Shakespeare, John Day, Samuel Daniel, Lady Mary Wroth, John Milton, and many others. “The Arcadia” is considered by scholars to be the earliest known use of a heroine named Pamela. And of course, Jeff Whitty and James Magruder were inspired by both the story and the music of the Go-Go's to create Head Over Heels!