It is natural that mankind should take great pride in the steady advance of its knowledge. The joy we feel in the contemplation of scientific progress is fully justified. One problem after another is solved by science; and the success of the past gives us ample reason for our hope that this process will go on, perhaps even at a quicker pace. But will it, can it, go on indefinitely?
It seems a little ridiculous to suppose that a day might come when all imaginable problems would be solved, so that there would be no questions left for which the human mind would crave an answer. We feel sure that our curiosity will never be completely satisfied and that the progress of knowledge will not come to a stop when it has reached its last goal.
It is commonly assumed that there are other imperative reasons why scientific advance cannot go on for ever. Most people believe in the existence of barriers that cannot be scaled by human reason and by human experience.
The final and perhaps the most important truths are thought to be permanently hidden from our eyes; the key to the Riddle of the Universe is believed to be buried in depths the access to which is barred to all mortals by the very nature of the Universe. According to this common belief, there are many questions which we can formulate, and whose meaning we can grasp completely, though it is definitely impossible to know their answer which is beyond the natural and necessary boundary of all knowledge. In regard to these questions a final ignorabimus is pronounced. Nature, it is said, does not wish her deepest secrets to be revealed; God has set a limit of knowledge which shall not be passed by his creatures, and beyond which faith must take the place of curiosity.
It is easy to understand how such a view originated, but it is not so clear why it should be considered to be a particularly pious or reverent attitude. Why should Nature seem more wonderful to us if she cannot be known completely ? Surely she does not wish to conceal anything on purpose, for she has no secrets, nothing to be ashamed of. On the contrary, the more
