813. "And His wife has made herself ready." This symbolically means that those who will belong to this church, namely, the New Jerusalem, are being gathered together, introduced to it, and instructed.

The wife symbolizes the Lord's New Church, namely, the New Jerusalem, as is clearly apparent from chapter 21 that comes later, where we find the following:

I... saw the holy city, New Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband. (Revelation 21:2)

And in the same chapter:

(An angel) came to me..., saying, "Come, I will show you the bride, the Lamb's wife." And he... showed me the great city, the holy Jerusalem, descending out of heaven from God... (Revelation 21:9-10)

The wife's making herself ready means, symbolically, that those who will belong to that Lord's New Church are being gathered together, introduced to it, and instructed. And because her making herself ready has the symbolic meaning, therefore it follows next that as a wife she was "arrayed in fine linen, clean and bright," which symbolizes an introduction through instruction. Moreover, for the same reason a white horse is also afterward described, which symbolizes an understanding of the Word provided for them by the Lord.

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.