At the olive press, the hard and bitter olives are partially crushed in order to extract the oil and to sweeten the fruit.
So, too, it is written, the body of man has to undergo a certain amount of pressure and adversity to enable the inner self to emerge.
But where is this self?
In the description of the menorah in scriptural texts, there are two olives, little hollow bulbs, one to the right and the other to the left of the stem, and these provide the oil for the lamps.
The right and the left, grace and severity, the two aspects of man, struggle against each other; they represent the need for friction and conflict as a part of the purification process.
It represents the refinement of the self that comes from adversity, when man cries out "Have mercy on me, Thou who art all merciful."
–Rabbi Adin Steinsaltz
From "Implications of the Menorah," in The Candle of God by Rabbi nAdin Steinsaltz