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.

5159. They see not only flower gardens there, but particularly orchards, wonderfully laid out, in endless and limitless variety. And in the trees they see fruits, glistening with the brightest heavenly colors, wonderfully shaped; and also palaces with ever changing decors, and doing this so harmoniously that the unfolding changes bring inexpressible pleasure to the mind. Inside, the rooms are arranged in such ways as are indescribable, astonishingly decorated as well.

Besides this there is conversation where one entertains the other in such a way that because together they are in agreement, their thought forms a perceptible harmony. One person's nature can be told apart from another's by their actions, by their way of speaking, from the paths they take, and from the changes of their expression at the particular things they say and hear. There are also very beautiful birds which, depending on the thoughts, appear colored, adorned with wings and feathers, and they fly. Besides this there are also countless kinds of gentle animals.