"Philosophers have disputed whether the explanation of the universe is to be found in matter or mind, in an inscrutable first cause, or in an intelligent Creator. But the first question which ought to be settled is, what is explanation ? When we demand that the universe shall be explained, what is it that we wish to know about the universe ?
"Now an isolated fact is usually said to be explained when its cause has been discovered. And if its cause cannot be ascertained, it is said to be an unexplained fact. My cold feet are explained by the existence of a draught. But we cannot explain the universe in this way. If the universe could be said to have a cause, then either that cause is the effect of a prior cause, or it is not. Either the chain of causes extends back in an infinite series, or there is somewhere a “first cause” which is not the effect of any prior cause. If the series is infinite, then no final and ultimate explanation is to be found. If there is a first cause, then this first cause is itself an unexplained fact. If by explaining a thing we mean assigning a cause for it, then a first cause is by hypothesis unexplained and inexplicable, since we cannot assign any prior cause to it. To explain the universe by something which is itself an ultimate mystery is surely no explanation."