Just as there are centers of sickness that can spread, there are any number of modes of benevolent influence, of goodness and light.
These beneficial centers also have the power to grow and draw to themselves that which comes under this influence.
But this attraction requires a certain level of being, more mature and powerful than the surrounding forces.
A farmer could not leave a field untilled and return expecting to find it covered with roses, or even wheat.
He will more likely find it overgrown with weeds and thorns.
The rose is a very pampered plant, so many things interfere with it, but the weeds have no trouble flourishing.
True, there have been experiments to develop a species of wheat that would have the resilience and strength of wild wheat, able to grow in any conditions, capable even of thrusting out the weeds.
But the fact is that our cultivated crops of flowers and food need more care than ever.
–Rabbi Adin Steinsaltz
From "Two Ways of Tikun," in In the Beginning by Rabbi Adin Steinsaltz