Before describing the ceremonial clothes of the priests, the Torah talks about keeping a flame alight in the Tabernacle (the eternal flame). The symbolism is a powerful one, that the spirit of God and of the people, burns constantly. The flame symbolizes the human spirit, that can burn or be extinguished. It symbolizes God. Something that combines the spiritualism, the physical, that can nourish and give life but that can also destroy.
The command was to have candelabrum of seven branches in the Tabernacle on which the western light would burn constantly. There are many explanations given as to why it should be the Western light, especially since we pray towards Jerusalem which was for most Israelites to their East.
The West is where the sun sets. In simplistic terms the sun goes down and the world is left in darkness. To keep the Western light going is to try to compensate for the darkness, to keep the light burning nevertheless.
In mystical terms it represents our need for ourselves as a people and as individuals to keep the flame of spirituality and Torah alive even if everything around us seems lost, dark, negative.