I cannot close this chapter without some allusion to a crafty employment of words only too well understood already by those who influence the popular mind. There is such a natural tendency to confusion in all ordinary human beings that if you repeatedly present to them two totally distinct things at the same time, they will, before long, associate them so closely as to consider them inseparable by their very nature. This is the reason why all those branches of education that train the mind in analysis are so valuable. To be able to distinguish between accidental connections of things or characteristics and necessary connections, is one of the best powers that education bestows upon us. By far the greater number of erroneous popular notions are due simply to the inability to make this distinction which belongs to all undisciplined minds. Calumnies, that have great influence over such minds, must lose their power as the habit of analysis enables people to separate ideas which the uncultivated mingle together. Insufficient analysis leads to a very common sort of confusion between the defectiveness of a part only and a defect pervading the whole. An invention (as often happens) does not visibly succeed on the first trial, and then the whole of the common public will at once declare the invention to be bad, when, in reality, it may be a good invention with a local defect, easily remediable. Suppose that a yacht misses stays, the common sort of criticism would be to say that she was a bad boat, when, in fact, her hull and everything else might be thoroughly well made, and the defect be due only to a miscalculation in the placing of her canvas. I have myself seen a small steel boat sink at her anchorage, and a crowd laugh at her as badly contrived, when her only defect was the unobserved starting of a rivet. The boat was fished up, the rivet replaced, and she leaked and sank no more. When Stephenson's locomotive did not go because its wheels slid on the rails, the vulgar spectators were delighted with the supposed failure of a benefactor of the human species, and set up a noise of jubilant derision. The invention, they had decided, was of no good, and they sang their own foolish _gaudeamus igitur_. Stephenson at once perceived that the only defect was want of weight, and he immediately proceeded to remedy it by loading the machine with ballast. So it is in thousands of cases. The common mind, untrained in analysis, condemns the whole as a failure, when the defect lies in some small part which the specialist, trained in analysis, seeks for and discovers.