In Leviticus 6:16, 'Aaron and his sons eating the remainder' signifies a person's reciprocation and making something one's own. This represents conjunction by means of love and charity. This is why they were commanded to eat it 'in a holy place.'

(References: Arcana Coelestia 2177)

The Lord's love is the sun of heaven, and it is natural for us to look above ourselves to the sun of this world in thinking about the Lord. It follows, then, that to be closer to the Lord we would climb into the highest places -- and indeed, people have been worshiping on mountains for ages. In fact, even steeples on modern churches are symbolic mountains. It makes sense, then, that a mountain in the Bible represents love to the Lord, the highest, purest love we human beings can experience. Mountains can also represent the desire for good that comes from the love of the Lord. Hills, meanwhile, represent a love of other people and a caring for them, and when "mountains" is used in the plural it generally represents both loves.