Heraclitus is famous for logos and fire. Logos is the word that is logical and true. Fire is the principle of all things. It acts as a conductor because the world is in a permanent state of change. Heraclitus was focused on change itself, and change makes things one. So fire is a symbol of change. Fire destroys things and rekindles things.  An example is that something perishes in fire while others emerge from fire. Therefore without fire destroying and rekindling things the world will seize to exist. The primacy of fire in his teaching is to show transformation causing constant shifting of things from growing up to their ultimate dying which is applicable in all nature. Heraclitus view change as making all things as one and anything that is opposite of fire cannot exist at all. It can be argued that Heraclitus believed in cyclical cosmogony where cosmos emanated from fire and degenerated into fire in a cyclical manner.