We Cannot Know That Anything Exists, Which We Do Not Know

It is often said, as though it were a self-evident truism, that we cannot know that anything exists, which we do not know. It is generally also implied, for reasons which remain obscure, that what can have no importance for us cannot be real. To go into this argument fully at our present stage would be impossible since it raises points requiring a considerable preliminary discussion. But certain reasons for rejecting the argument may be noticed at once. There is no reason why what cannot have any practical importance for us should not be real. If theoretical importance is included, everything real is of some importance to us. As persons desire us of knowing the truth about the universe, we have some