" hat is the fundamental characteristic of the crocodile? The answer is clear: to swallow human beings. How is one, in constructing the crocodile, to secure that he should swallow people? The answer is clearer still: construct him hollow. It was settled by physics long ago that Nature abhors a vacuum. Hence the inside of the crocodile must be hollow so that it may abhor the vacuum, and consequently swallow and so fill itself with anything it can come across. And that is the sole rational cause why every crocodile swallows men. It is not the same in the constitution of man: the emptier a man’s head is, for instance, the less he feels the thirst to fill it, and that is the one exception to the general rule. "

― Fyodor Dostoevsky , The Crocodile