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.

1141. Those who are here named 'sons of Japheth' were all such people as possessed external worship corresponding to internal, that is, people who lived in simplicity, friendship, and mutual charity, and knew no other doctrinal teachings than those which existed as external forms of ritual. Those who are named 'sons of Ham' were people who possessed corrupted internal worship. Those who are called 'sons of Canaan' were people who possessed external worship separated from internal. Those who are referred to as 'sons of Shem' were internal men, who worshipped the Lord and loved the neighbour. Their Church closely resembled the true Christian Church with us.