All of these tie in to "The Four Agreements", in that they help us begin to understand the complex astrology (more like astronomy really) of the Toltec, who's beliefs Mr. Ruiz is now sharing with the world, (and by doing so, unquestionably making it a better place).
A review of The Four Agreements
More about Quetzecoatl as morning and evening star (Venus, if you will) The Plumed Serpant