Source: Hubblesite.org

"Whatever be our conception of the universe we must, it is obvious, start somehow; we must begin with something; and the something with which we begin, from the very fact that we do begin with it, must itself be without explanation, since, if something else were invoked to explain it, then the 'something else' must needs be logically prior to that which it is invoked to explain. Thus the 'something' being explained by a logically prior 'something else' could not have been ultimate."

-- C. E. M. Joad