A Note on Religion: If you have one you should read this.
Nodes: What they are and how they work. Everyone should read this.
Spirits, Deities and Demons: The complete list. You only need to read this if you are a shaman, witch, demonist, or medium.
Spells: How spells are cast in Egregore. You only need to read this if you are a spellcaster. 
List of Spells: The complete list of common spells. You only need to read this if you are a spellcaster.