A light is a symbol, as is the act of turning it off. Symbols are given power by people

[bcholmes]

At 9:30 p.m., the conclusion of the second global Earth Hour, the meter at Toronto Hydro's control centre that measures city-wide electricity demand hit 2,545 megawatts – 15 per cent below typical demand at that time and 7 per cent below the lowest demand during Earth Hour in 2008.

— "Earth Hour II is a smash"