Oil
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.
Exodus 30:22-33
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Moreover Yahweh spoke to Moses, saying,
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"Also take fine spices: of liquid myrrh, five hundred shekels; and of fragrant cinnamon half as much, even two hundred and fifty; and of fragrant cane, two hundred and fifty;
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and of cassia five hundred, after the shekel of the sanctuary; and a hin of olive oil.
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You shall make it a holy anointing oil, a perfume compounded after the art of the perfumer: it shall be a holy anointing oil.
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You shall use it to anoint the Tent of Meeting, the ark of the testimony,
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the table and all its articles, the lampstand and its accessories, the altar of incense,
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the altar of burnt offering with all its utensils, and the basin with its base.
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You shall sanctify them, that they may be most holy. Whatever touches them shall be holy.
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You shall anoint Aaron and his sons, and sanctify them, that they may minister to me in the priest's office.
31
You shall speak to the children of Israel, saying, 'This shall be a holy anointing oil to me throughout your generations.
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It shall not be poured on man's flesh, neither shall you make any like it, according to its composition: it is holy. It shall be holy to you.
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Whoever compounds any like it, or whoever puts any of it on a stranger, he shall be cut off from his people.'"
