Ah! the things we don't know, the things we don't know!" He was relapsing into his anger, his hatred of science, which he scorned since it had left him scared and powerless beside the deathbed of his wife and his daughter.

"You ask for certainties," he resumed, "but assuredly it is not medicine which will give you them.

Listen for a moment to those gentlemen and you will be edified.

Is it not beautiful, all that confusion in which so many opinions clash together?
Certainly there are ailments with which one is thoroughly acquainted, even to the most minute details of their evolution; there are remedies also, the effects of which have been studied with the most scrupulous care; but the thing that one does not know, that one cannot know, is the relation of the remedy to the ailment, for there are as many cases as there may be patients, each liable to variation, so that experimentation begins afresh every time.

This is why the practice of medicine remains an art, for there can be no experimental finality in it.