Oil -- typically olive oil -- symbolizes the good that comes from celestial love. Celestial love is love of the Lord, the highest and purest love we can have. The good of celestial love is the desire to be good springing from celestial love: Wanting to do the Lord's will because you love Him. That's not a state many reach, even in heaven, but it's a beautiful goal. This representation makes sense based on the idea that the sun -- the source of all natural light and heat, and thus all natural life -- represents the Lord, the source of all spiritual light, heat and life. Burning oil was the most pure fire available in Biblical times, thus the closest representation of the sun people could create.

1588. 'Like the garden of Jehovah' means the rational concepts in the external man. This is clear from the meaning of 'the garden of Jehovah' as intelligence, dealt with in 100, consequently the rational which comes in between the internal man and the external man. The rational is intelligence as it exists in the external man. It is called 'the garden of Jehovah' when the rational is celestial, that is, when it has a celestial origin, as was the case with the Most Ancient Church. This is described in Isaiah as follows,

Jehovah will comfort Zion, He will comfort all her waste places, and will make her wilderness like Eden and her desert like the garden of ]Jehovah. Joy and gladness will be found in her, confession and the voice of song. Isaiah 51:3.

When however the rational is spiritual, that is, when it has a spiritual origin, as was the case with the Ancient Church, the expression 'the garden of God' is used, as in Ezekiel,

Full of wisdom, and perfect in beauty, you were in Eden, the garden of God. Ezekiel 28:12-13.

A person's rational is compared to a garden because this is how it is represented in heaven. It is man's rational that manifests itself in just this way when that which is celestial-spiritual flows into it from the Lord. Indeed it is this which presents to view the paradise gardens whose magnificence and beauty surpass everything the human mind can imagine. This is the effect which the influx of celestial-spiritual light from the Lord produces, as dealt with already in 1042, 1043. It is not the loveliness and beauty of these gardens that stir the emotions but the celestial-spiritual elements that live within them.