III. _Mr. Buckle's Theory concerning Skepticism._--One of the laws of history which Mr. Buckle considers himself to have established, if not discovered, is that a spirit of skepticism precedes necessarily the progress of knowledge, and therefore of civilization. By skepticism he means a doubt of the truth of received opinions. He asserts that "a spirit of doubt" is the necessary antecedent to "the love of inquiry." (Vol. I. p. 242, Am. ed.) "Doubt must intervene before investigation can begin. Here, then, we have the act of doubting as the originator, or at all events the necessary antecedent, of all progress." If this were so, progress would be impossible. For the great groundwork of knowledge for each generation must be laid in the minds of children; and children learn, not by doubting, but by believing. Children are actuated at the same time by an insatiable curiosity and an unquestioning faith. They ask the reason of everything, and they accept every reason which is given them. If they stopped to question and to doubt, they would learn very little. But by not doubting at all, while they are made to believe some errors, they acquire an immense amount of information. Kind Mother Nature understands the process of learning and the principle of progress much better than Mr. Buckle, and fortunately supplies every new generation of children with an ardent desire for knowledge, and a disposition to believe everything they hear. Perhaps, however, Mr. Buckle refers to men rather than children. He may not insist on children's stopping to question everything they hear before they believe. But in men perhaps this spirit is essential to progress. What great skeptics, then, have been also great discoverers? Which was the greatest discoverer, Leibnitz or Bayle, Sir Isaac Newton or Voltaire? A faith amounting nearly to credulity is almost essential to discovery,--a faith which foresees what it cannot prove, which follows suggestions and hints, and so traces the faintest impressions left by the flying footsteps of truth. The attitude of the intellect in all discovery is not that of doubt, but of faith. The discoverer always appears to critical and skeptical men as a visionary.