As those in the Jewish religious community know, on Shabbos (Saturday, the Sabbath), electricity is considered to have the halacha (Jewish law status) of fire. (Just as one does not light or put out a fire on Shabbos, one does not turn on or off a light on Shabbos, one leaves it on in advance or connects a timer to it.)

At the children's science museum yesterday, I saw this reproduction of a notice from 250 years ago (note the date, 1753):