The Sun is a symbol for your Highest Self.
While describing the Tarot Lovers card, Mathers says "Here it is yellow instead of white, showing that it is our day star, the actual physical sun whence we draw not only energy and life, but also, says the Ageless Wisdom, potential con- sciousness. The sun is not merely a center of physical force, a thing in the sky. It is the body of a Being." 
- Mathers, S. L. MacGregor. The Tarot: Its Occult Significance, Use in Fortune-Telling, and Method of Play, Etc. Kindle Edition, 1888. p. 73