The first greek philosophers believed that the universe was built using four basic elements which are earth, water, air and fire. All of these elements could be mixed to create the different materials found on earth. In the sky there was another element known as the Fifth Element, Quintessence or Èter.

Thus the earth represents the solid state, water the liquid state, air the gaseous state and fire the imponderable state.

The Fifth Element or etheric represents such a subtle and lively state of matter that it is no longer atomic and is the original cosmic fluid, the astral light or soul of the world.

The Fifth Element has been conceived to safeguard the balance between good and evil, especially if they conflict.

https://www.youtube.com/watch?v=zlM26hvOzxQ