What is the origin of the classic metaphor "Falling in love"?

I think this is an example of what is called a dead metaphor, because you do not actually visualize falling when you understand the meaning of the phrase. Still, it is more poetic to say “I am falling in love” than saying “I have decided that I love this girl I met last week”.
So where does it come from?
Did it first appear someplace like Shakespeare?
Or is the origin simply unknown, a part of the public domain so to speak?