I am certain that Firebird, as associated with the primordial element of fire, could be linked up with the old Persian cult of perpetual flame and the Zoroastrian religion. Furthermore, albeit more loosely, the ancient Greek philosopher, Heraclitus, was known for his metaphors, attempting to grasp the dynamics of creation, put as workings of fire or energy comparable to fire. Heraclitus was known as the "dark" or "dim" philosopher, which is to be understood that his teachings were prone to various interpretations and not explicit in their meaning, therefore hard to understand for casual recipients. Apart from that, Frederick Nietzsche, the author of "Thus Has Spoken Zarathustra", in his works, comes forward with the notion of eternal recurrence, the infinite loop the existence is trapped within - which, to my evaluation, would actually destine the universe to collapse, as soon as the loop ties up - nonetheless, such an idea could also definitely be associated with the cycles of death and rebirth, characteristic to the Firebird. Returning to the Heraclitus, he expressed the belief that the world rises and dwindles in the pattern of consecutive cycles, which puts his cosmology under the umbrella of cyclic models. Cyclic models, for nowadays, are oft dismissed, nonetheless, in science and exploration, no word is ever final.