Mythology: in ancient times the olive tree was the most beloved and venerated plant, and the one who was found to fall one was condemned to death. Why this plant was so venerated is explained by Greek mythology.

Zeus decided that the Earth would be granted to either Athena und Poseidon, according to who was able to offer the most useful gift for humanity.
Poseidon threw his trident against a rock and made seawater pour out. Athena struck the ground and ordered the earth to produce a new and wonderful tree; and so the olive tree was born. Olympus’s assembly decided that this was the most useful miracle and declared Athena the winner.

Literary sources tell about great celebration in Athena’s honour, where the winners of the various competitions received amphorae full of the precious oil from the goddess’s olive groves.