According to Greek mythology, we have Athena to thank for the olive-tree. The goddess and Poseidon competed for the affection of the Greeks…

He had provided a wonderful salt-water spring…

 
Athena turned a thorny bush into an olea, an unarmed tree laden with wonderful olives at the site of the Erechteion. (The said olive tree is still believed to be standing there.)

Athletes would smear their bodies with olive oil before Gymnasium and Stadium games.

And very soon it would gain the sacred reputation that it is still  enjoying today.

 The Arabs even granted it the BARRAKA !

Christians used it for the Extreme Unction and to anoint their kings. (Jesus meant « the anointing of the lord ».)

 But Ancient Greeks would also cover their swing ploughshares with it for the first furrow… it was a propitiatory gesture. In addition, oil lamps and candles had freed them from darkness. Indeed, nights must have been long and oppressive before the electricity was invented !
It is only natural that in such troubled times as our own, man should once again turn to the olive tree, a symbol of peace.