'Similarity' and 'contagion'

Growing up in Greece, I spent my summers at my grandparents’ home in a small coastal village in the region of Chalkidiki. It was warm and sunny, and I passed most of my time playing in the streets with my cousins. But occasionally, the summer storms brought torrential rain. You could see them coming from far away, with black clouds looming over the horizon, lit up by lightning.
As I rushed home, I was intrigued to see my grandparents prepare for the thunderstorm. Grandma would cover a large mirror on the living room wall with a dark cloth and throw a blanket over the TV. Meanwhile, Grandpa would climb a ladder to remove the light bulb over the patio door. Then they switched off all the lights in the house and waited the storm out.
I never understood why they did all this. When I asked, they said that light attracts lightning. At least that was what people said, so better to be on the safe side.

'Similarity' and 'contagion': Anthropologist traces the psychological roots of magical thinking