Answer: We see that there are always two opposing forces in nature, like plus and minus, north and south; one cannot exist without the other. In every phenomenon we see an integration of two opposing forces; moreover, the negative force is no less vital than the positive.
Once there was a case where it was attempted to exterminate all the wolves that were attacking the flocks, and this brought catastrophic results. This created an imbalance in nature and all kinds of problems began: epidemics among the sheep and other wild animals the wolves normally ate.
In nature there are no positive or negative forces. The two forces are beneficial: Both the positive force and the negative force must exist in harmony with each other.
Only on the human level does the singular power of our ego operate, a negative force against which there is no positive force with which it should be in harmony. So we need to attain connection between us to use this negative force and transform it into a positive one.
From the 1st part of the Daily Kabbalah Lesson 6/8/14, Writings of Baal HaSulam