Evil is not simply a sum of certain drives and impulses but is the result of man's inability to separate himself from the corrupting effect "knowing."
It is like the consequences of realizing that one can get away with a lie.
So long as — like in nature — it is inconceivable for a wrong action to succeed, there is no danger in multiplying knowledge.
But once man learns the power of untruth, that it is possible to satisfy his desire with a lie, this knowledge can be disastrous.
Evil in itself is therefore not dangerous.
It is the knowledge, the interiorizing of evil, that makes for corruption.
Just as some substances are injurious to the body and others can be swallowed without harm, evil is an indifferent substance for the angels but dangerous to man.
It is for this reason that God did not want man to eat of the Tree.
He wanted man to be holy and avoid the terrible inner struggle of sin, the historical chain of rising and falling.
But the question remains: Why was God troubled by the possibility of Adam's taking of the Tree of Life?
After all, immortality had been granted to man in the beginning.
The answer, according to Sages such as the Ramban, is that everything has its time, and that in order to relate to certain things properly one must be mature enough to recognize and avoid their harmful influences.
To try to relate before that invites sickness and disaster.
The first man, early man, was still too immature to be like "one of us."
Perhaps the "end of days" refers to the time when the spirit of uncleanness will pass from the earth.
If we can go through the trouble and sorrow of this world, we may reach that stage of being in which the knowledge of good and evil will have no power to influence us and we will be like the celestial beings.
In the beginning, God wished to save us from the throes of the war within us.
–Rabbi Adin Steinsaltz
From “The Tree of Knowledge” from In the Beginning by Rabbi Adin Steinsaltz