Again, the scientific method tends to increase our knowledge by the very fact that it discourages unreasoning faith. The scientist realizes that most of his so-called facts are probably errors and so he is willing to harbor doubts of their truth and to seek for something better. Like Socrates he boldly says "I know that I am ignorant." He realizes, in fact, that error, when it is constantly under fire, is bound to be resolved in the long run into something approximating the truth. As Nicolas pointed out 500 years ago, nothing is utterly and absolutely true and nothing is utterly and absolutely false. There is always a germ of truth in the worst error, and there is always a residuum of error in the soundest truth. Therefore, an error is fatal only when it is hidden from the white light of investigation. Herein lies the difference between the modern scientist and the moralist. The former holds nothing sacred, not even his own axioms; the latter lays things down as law and then makes it a crime to doubt them. It is in this way--by submitting every idea to a searching, pitiless, unending examination--that the world is increasing its store of what may be called, for the sake of clearness, absolute knowledge. Error always precedes truth, and it is extremely probable that the vast majority of ideas held by men of today--even the sanest and wisest men--are delusions, but with the passing of the years our stock of truth grows larger and larger. "A conviction," says Nietzsche, "always has its history--its previous forms, its tentative forms, its states of error. It becomes a conviction, indeed, only after having been _not_ a conviction, and then _hardly_ a conviction. No doubt falsehood is one of these embryonic forms of conviction. Sometimes only a change of persons is needed to transform one into the other. That which, in the son, is a conviction, was, in the father, still a falsehood."[5] The tendency of intelligent men, in a word, is to approach nearer and nearer the truth, by the processes of rejection, revision and invention. Many old ideas are rejected by each new generation, but there always remain a few that survive. We no longer believe with the cave-men that the thunder is the voice of an angry god and the lightning the flash of his sword, but we still believe, as they did, that wood floats upon water, that seeds sprout and give forth plants, that a roof keeps off the rain and that a child, if it lives long enough, will inevitably grow into a man or a woman. Such ideas may be called truths. If we deny them we must deny at once that the world exists and that we exist ourselves.