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.

4696. 'And behold, the sun and the moon' means natural good and natural truth. This is clear from the meaning of 'the sun' as celestial good, dealt with in 1529, 1530, 2120, 2441, 2495, 3636, 3643, 4060; and from the meaning of 'the moon' as spiritual good, which is truth, dealt with in 1529, 1530, 2495. In the highest sense 'the sun' means the Lord because He is seen as the sun by those in heaven who are governed by celestial love, and in the highest sense 'the moon' too means the Lord because He is seen as the moon by those in heaven who are governed by spiritual love. Also He is the source of every ray of light in heaven. Consequently the light received from the sun there is the celestial form of love, which is good, and the light received from the moon there is the spiritual form of love, which is truth. Here therefore 'the sun' means natural good and 'the moon' natural truth, since these two sources of light are used to refer to Jacob and Leah (as is evident from verse 10, where Jacob says, 'Shall we indeed come - I and your mother, and your brothers - to bow down to you to the earth?') and 'Jacob' represents natural good and 'Leah' natural truth, as shown already in various places. The Divine which comes from the Lord is in the highest sense the Divine within Him, but in the relative sense is the Divine going forth from Him. The Divine good received from Him is that which is called celestial, and the Divine truth received from Him is that which is referred to as spiritual. When the rational receives these it is in this case the good and truth of the rational that are meant; but when the natural receives them it is the good and truth of the natural that are meant. Here the good and truth of the natural are meant because the words used refer to Jacob and Leah.