The Phoenix symbolizes the spark generated by the fusion of the dualistic nature of the human psyche. The Union of our polarities. The product of what I believe is what Shakespeare would call "Grinding of The Mill".
In eastern myths the phoenix symbolizes the union of an ancient civilization called. "The Dragon & Bird Clan", To the Minoans, "Atlantis & Lemuria".
In an older context. The Phoenix is the product of a term called "Order out of Chaos'. Hence, the term "Rising from The Ashes".