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.

10178. 'With pieces of shittim wood you shall make it' means from love that is Divine. This is clear from the meaning of 'shittim wood' as the good of merit and of righteousness, which is the Lord's alone, dealt with in 9472, 9486, 9715. The reason why love as well is meant is that when the Lord was in the world He was motivated by Divine Love to fight against all the hells and overcome them, and in so doing to save the human race, as a result of which He alone has earned merit, and has become righteousness, see 9486, 9715, 9809, 10019, 10152; and the good of merit which is the Lord's is therefore His Divine Love. The reason why 'shittim wood' has so profound a meaning is that all things which exist in earth's three kingdoms - the animal, vegetable, and mineral kingdoms - serve to mean spiritual and celestial realities, or else their opposites. (For the whole natural order is a theatre representative of the Lord's kingdom, see the places referred to in 9280.) And 'wood' means in general the good of love, and in particular the good of merit, 2784, 2812, 3720, 4943, 8354, 8740. So it is that in the highest sense 'wood' means Divine Good; for all things serving in the internal sense to mean aspects of the Church and of heaven serve in the highest sense to mean Divine realities.