If, for instance, one had to construct a new crocodile, the question would naturally present itself. What is the fundamental characteristic of the crocodile? The answer is to swallow human beings. How is one, in constructing the crocodile, to secure that he should swallow people? The answer is clearer construct him hollow. It was settled by physics long ago that Nature abhors a vacuum. - Taken from "The An Extraordinary Incident" written by Fyodor Dostoyevsky