Why is there something rather than nothing?

"It has been said that the question Why is there something rather than nothing? is so profound that it would occur only to a metaphysician, yet so simple that it would occur only to a child."

"What options do you have for resolving the mystery of existence once you let go of the God hypothesis? Well, you might expect that science will someday explain not only how the world is, but why is it. This, at least, is the hope of Dawkins, who looks to theoretical physics for an answer. “Maybe the ‘inflation’ that physicists postulate as occupying some fraction of the first yoctosecond of the universe’s existence will turn out, when it is better understood, to be a cosmological crane to stand alongside Darwin’s biological one,” Dawkins has written. 

Stephen Hawking, who is actually a practicing cosmologist, takes a different approach. Hawking came up with a theoretical model in which the universe, though finite in time, is completely self-contained, without beginning or end. In this “no-boundary” model, he argued, there is no need for a creator, divine or otherwise. Yet even Hawking doubts that his set of equations can yield a complete resolution to the mystery of existence. “What is it that breathes fire into the equations and makes a universe for them to describe?” he plaintively asks. “Why does the universe go through all the bother of existing?

–"Why Does the World Exist? An Existential Detective Story" by Jim Holt

I'm about to begin this existential story. Science is still trying to figure "how" the universe came to exist but what came before the Big Bang?