More to say... Darkness Rises... It falls when joy reigns

Darkness falls is a metaphor which comes from when sun goes down, darkness "falls" to take its place from down to up. Darkness rises could be used just as well but it makes you think about something rising and referred to as "darkness" such as demons or zombies.

Whatever the way you like to take it, you do know what I mean.

*...from up to down.