Based on the short story "The Sandman" by German author E.T.A. Hoffmann.
Nathanael falls madly in love with Olimpia, Professor Spallanzani's daughter. All she ever says is "Ah, ah!" He is convinced, that she really understands him.
In the end, she turns out to be an automaton. A life like mechanical doll and early version of artificial beings we might see in the future. Back in the time 200 years ago, the options were limited to precision mechanics and possibly a touch of magic.
With technology advancing at the current pace, it might indeed soon be difficult, to distinguish between real human and machine.