A partial explanation of this may be found in the fact that the most uncongenial tasks are also the worst paid, while the congenial tasks command the high emoluments. Generally speaking there is no distinction between one laborer and another in the same field--except where the eminently fair method of piece work can be employed. Even the skilled laborer is usually paid by the day, and the amount he is to receive is commonly fixed by a Union regardless of his efficiency as compared with other laborers of the same class. And there is no possibility of his receiving any such sums as the man who plans the work, but does nothing with his own hands. It has always been so. Just as "those who think must govern those that toil," so the thinker must command the high reward. Partly this is because man, considered as a mere toiler, is so relatively inefficient a worker. When he strives to work with his hands, his effort is but a pitiful one; he can by no possibility compete (as regards mere quantity of labor) with the ox and the horse. He is impatient of his own puerile efforts. It is only when he brings the products of ingenuity to his aid that he is able to show his superiority, and to justify his own egotism. So it is that in every age he has striven to find means of adding to his feeble powers of body through the use of his relatively gigantic powers of mind. And in proportion as he thus is able to "make his head work for his hands" as the saying goes, he verges toward the heights of civilization. To accomplish this more and more fully has ever been the task of science as applied to the industries. It will be our object in the ensuing chapters to inquire how far science has accomplished the protean task thus set for it. We shall see that much has been done; but that much still remains to be done. In proportion as the problems are unsolved, science is reproached for its shortcomings--and stimulated to new efforts. In proportion as labor has been minimized and production increased--in just that proportion has science justified itself; and in the same proportion has the Conquest of Nature been carried toward completion. II HOW WORK IS DONE