Why does Maria flee the flashlight beam?

In the first section of Fritz Lang's "Metropolis," the mad scientist, Rotwang, descends into catacombs under the workers' city to capture their moral leader, Maria. He easily succeeds, herding her into his house/laboratory through use of a flashlight, the beam from which seems to terrify her. Why? She has seen electric lights before; they're all over the workers' city.