The Sephirot, are the vessels images in this diagram of the Kabbalstic Tree of Life. They became the goal of souls to redeem those qualities as their mission on earth. The vessel could not hold the Light and therefore shattered the shells that held it, klipot, and they fell to earth. And that vessel is us: all souls, past and present. The contained Light created is what Kabbalists call the vessel. As such, in order to share Its essence, It needed to create something to receive all Its beneficence. The nature of the Light is that of endless giving.
Before the Big Bang, before our universe and planet, the Light was the only thing that existed.
Kabbalists identify the source of energy in the universe as Light.