On earth good needs evil.

"On earth good needs evil. Yes, in order to manifest, good needs
evil; otherwise, it goes to sleep, because there is no longer
anything there to stimulate it. Evil excites good, stimulates
good, and then good acts. It is thanks to evil that good is good.
If ugliness did not exist, we would not know how beautiful beauty
is, and, in the same way, if there were no evil, we would not
know what good is.
You want to annihilate evil? Fine, but the good will also be
annihilated, because evil is like the roots of good; if you tear
up the roots of a tree, it dies. Of course, that does not mean
that we must nurture and strengthen evil. No, it is strong enough
as it is; it does not need our help. But we must not try to
eradicate it either, and in any case it can’t be done. But we
need to know what attitude to adopt towards it so we can use it
for the good."

Omraam Mikhaël Aïvanhov