The Phoenix is a bird of fire that has many powers. When killed (or dying of natural causes) it falls to ashes and then is reborn within them. It is a never-ending cicle. That’s where the idiom “rise from the ashes” comes from. 🙂 The pheonix is a metaphor for that. It is also often used for people who never give up, no matter what has happened to them. It’s also a symbol for re-incarnation. It has loads of other meanings, stories, etc. Probably why they picked it as the place for Henry’s brith. 🙂