Why olive oil? The first answer is because it was ubiquitous in the ancient
East. The midrash suggests
additional answers. The olive branch was
a sign of peace. One reason it is such a
sign is because it takes five years before the olive tree produces olives. There must be a time of peace in order for
farmers to tend to their olive grove. Thus
one cannot cultivate such a crop during times of war.
In addition the oil must be pure. The Etz Hayim commentary points out that the fuel for the ner tamid must be uncontaminated by jealousy, selfishness, pride or greed. Given the care and nurturing, peace and tranquility, required to produce olive oil this is why it was the most prized fuel for lighting fire the eternal light. In fact an olive tree can live for 500 years!
The meaning of olive oil and the olive tree is that it requires our hands to nurture and sustain it. It requires relative peace and quiet in order to grow. This is why it was so valued. It is interesting to reflect on these qualities in an age when we are overly dependent on crude oil. It is inarguable that our need for oil leads to conflict. Do I need to recite examples? Moreover, our use of oil causes the despoliation of the environment. Is this still a debatable point?
Imagine a world dependent instead on the produce of our own hands. I understand that my life might be denied its many conveniences. Nonetheless if the fuel I required depended on my caring for a tree I might become more cognizant of my overuse and over-dependence on fuel. And then the olive tree would become not only the symbol of peace it has been since antiquity but the cause of peace.