Lord Bacon, the great master of practical wisdom, has said that "the effort to extend the dominion of man over nature is the most healthy and most noble of all ambitions." "The empire of man," he adds, "over material things has for its only foundation the sciences and the arts."[24] A great deal of the knowledge which constitutes this dominion has been the property of society, handed down from the earliest ages. No one can tell, for instance, how the art of leavening bread was introduced amongst mankind; and yet this process, now so familiar to all, contributes as much, if not more, than any other art to the wholesome and agreeable preparation of our food. Leavening bread is a branch of chemistry, and, like that process, many other processes of chemistry have been the common property of civilized man from time immemorial. Within a few centuries, however, science has applied its discoveries to the perfection of the arts; and in proportion as capital has been at hand to encourage science, has the progress of the application been certain and rapid. The old Alchemists, or hunters after the philosopher's stone, sought to create capital by their discoveries. They could not make gold, but they discovered certain principles which have done as much for the creation of utility in a few hundred years as the rude manual labour of all mankind during the same period. Let it not be supposed that we wish to depreciate manual labour. We only wish to show that labour is incomparably more prolific when directed by science. Mahomet Bey, the ruler of Tunis, was dethroned by his subjects. He had the reputation of possessing the philosopher's stone, or the art of turning common metals into gold. The Dey of Algiers restored him to his throne upon condition that the secret should be communicated to him. Mahomet, with great pomp and solemnity, sent the Dey of Algiers a plough. This was so far well. He intimated that to compel production by labour is to make a nation rich. But had he been able to transmit some of the science which now controls and guides the operations of the plough--the chemical knowledge which teaches the proper application of manures to soils--the rotation of crops introduced by the turnip-husbandry, which renders it unnecessary that the ground should ever be idle,--he would have gone farther towards communicating the real philosopher's stone.