There is no classification of the universe that is not arbitrary and conjectural. The reason is very simple: we do not know what the universe is .... One might say more; one might suspect that there is no universe in the organic, unifying sense conferred by that ambitious word .... The impossibility of penetrating the divine scheme of the universe cannot dissuade us, though, from offering up human schemes, even if we are aware they are provisional. We are thus introduced to a new principle of relativity which holds that all observers are not led by the same physical evidence to the same picture of the universe. Whenever a mind of true greatness and genius occupies itself with language, this phenomenon becomes manifest in reality .... The re...