[5] It is very evident, I take it, that the principal function of all science is the widening of our perceptions. The chief argument for idealism used to be the axiom that our power of perception was necessarily limited and that it would be limited forever. This may be true still, but it is now apparent that these limits are being indefinitely extended, and may be extended, in future, almost infinitely. A thousand years ago, if any one had laid down the thesis that malaria was caused by minute animals, he would have been dismissed as a lunatic, because it was evident that no one could see these animals, and it was evident, too--that is to say, the scientists of that time held it to be evident--that this inability to see them would never be removed, because the human eye would always remain substantially as it was. But now we know that the microscope may increase the eye's power of perception a thousandfold. When we consider the fact that the spectroscope has enabled us to make a chemical analysis of the sun, that the telephone has enabled us to hear 2,000 miles and that the x-rays have enabled us to see through flesh and bone, we must admit without reservation, that our power of perception, at some future day, may be infinite. And if we admit this we must admit the essential possibility of the superman. [6] "_Cours de philosophie positive_," tr. by Helen Martineau; London, 1853. VI CHRISTIANITY Nietzsche's astonishingly keen and fearless criticism of Christianity has probably sent forth wider ripples than any other stone he ever heaved into the pool of philistine contentment. He opened his attack in "_Menschliches allzu Menschliches_," the first book of his maturity, and he was still at it, in full fuming and fury, in "_Der Antichrist_," the last thing he was destined to write. The closing chapter of "_Der Antichrist_"--his swan song--contains his famous phillipic, beginning "I condemn." It recalls Zola's "_j'accuse_" letter in the Dreyfus case, but it is infinitely more sweeping and infinitely more uproarious and daring.