'An olive' signifies love and charity, because 'the olive tree' signifies the celestial church, and so 'the olive,' which is its fruit, signifies celestial love, which love is love to the Lord. This is why the oil which was used to anoint all the holy things of the church, signifies the same love. This oil which was called 'the oil of holiness' was produced from olives, and mixed with aromatics, as in Exodus 19:23, 24, and the lamps of the candelabra in the tabernacle were made to burn every evening with olive oil, as in Exodus 27:20 and Leviticus 24:2. 'An olive,' as in Isaiah 17:6, signifies celestial remains.

(Референце: Arcana Coelestia 886 [1-2])