Because the methods have been so fully explained and illustrated as to have grown familiar, a vast host of investigators, very few of whom possess scientific genius, are at work to-day extending our scientific knowledge. So the methods of historical criticism--so the methods of using statistics--are to-day profitably applied by many men with no such original gift as would have made them competent critics or statisticians had not the paths been cut by a few great men and trodden since by hundreds of feet. All that is needed is imitation--intelligent and careful imitation. Nevertheless, there remains this sharp contrast between knowledge of the facts of applied science and knowledge of the methods, that whereas there is no radical difference between the ability of one man and that of another to use a mechanical invention, such as a steam plough or an electric motor-car, there is all the difference in the world between the power of one intellect and another to use a method for the purposes of fresh discovery. Knowledge fossilised in a concrete invention or even in a mathematical formula is a sort of tool ready to every hand. But a method, though serviceable to everybody, becomes eminently fruitful only when wielded by the same kind of original genius as that which made discoveries by the less perfect methods of older days. This is apparent even in inquiries which seem to reside chiefly in collection and computation. Everybody tries nowadays to use statistics. Many people do use them profitably. But the people who by means of statistics can throw really fresh and brilliant light on a problem are as few as ever they were. [Sidenote: Advantage of Modern over Old Thinkers] When we turn to the exercise of speculative thought on subjects not amenable to strictly scientific--that is to say, to exact--methods, the gain which has come to mankind by the labour of past ages is of a different order. Metaphysics, ethics, and theology, to take the most obvious examples, are all of them the richer for the thoughts of philosophers in the past. A number of distinctions have been drawn, and a number of classifications made, a number of confusions, often verbal, have been cleared up, a number of fallacies detected, a number of technical terms invented, whereby the modern speculator enjoys a great advantage over his predecessor. His mind has been clarified, and many new aspects of the old problems have been presented, so that he is better able to see all round the old problems. [Sidenote: The Living Thought of Past Ages]