"To-morrow is Saint Valentine's day,
All in the morning betime,
And I a maid at your window,
To be your Valentine.
Then up he rose, and donn'd his clothes,
And dupp'd the chamber-door;
Let in the maid, that out a maid
Never departed more."
Ophelia in Hamlet (1600–1601), Act IV, Scene 5 - William Shakespeare
See here the Hearts, hearts, hearts collection to find more Valentine's Day Images