Scientists can account for the organization of the physical universe. They can trace how the individual things and forces within it causally interact. They can shed light on how the universe as a whole has, in the course of its history, evolved from one state into another. But when it comes to the ultimate origin of reality, they have nothing to say. That is an enigma best left to metaphysics, or to theology, or to poetic wonderment, or to silence.

— Jim Holt from book “Why does the world exist?”