Gradually then he will substitute for the natural world an artificial world, molded nearer to his heart's desire. Man the Artifex will ultimately master Nature and reign supreme over his own creation until chaos shall come again. In the ancient drama it was _deus ex machina_ that came in at the end to solve the problems of the play. It is to the same supernatural agency, the divinity in machinery, that we must look for the salvation of society. It is by means of applied science that the earth can be made habitable and a decent human life made possible. Creative evolution is at last becoming conscious. II NITROGEN PRESERVER AND DESTROYER OF LIFE In the eyes of the chemist the Great War was essentially a series of explosive reactions resulting in the liberation of nitrogen. Nothing like it has been seen in any previous wars. The first battles were fought with cellulose, mostly in the form of clubs. The next were fought with silica, mostly in the form of flint arrowheads and spear-points. Then came the metals, bronze to begin with and later iron. The nitrogenous era in warfare began when Friar Roger Bacon or Friar Schwartz--whichever it was--ground together in his mortar saltpeter, charcoal and sulfur. The Chinese, to be sure, had invented gunpowder long before, but they--poor innocents--did not know of anything worse to do with it than to make it into fire-crackers. With the introduction of "villainous saltpeter" war ceased to be the vocation of the nobleman and since the nobleman had no other vocation he began to become extinct. A bullet fired from a mile away is no respecter of persons. It is just as likely to kill a knight as a peasant, and a brave man as a coward. You cannot fence with a cannon ball nor overawe it with a plumed hat. The only thing you can do is to hide and shoot back. Now you cannot hide if you send up a column of smoke by day and a pillar of fire by night--the most conspicuous of signals--every time you shoot. So the next step was the invention of a smokeless powder. In this the oxygen necessary for the combustion is already in such close combination with its fuel, the carbon and hydrogen, that no black particles of carbon can get away unburnt. In the old-fashioned gunpowder the oxygen necessary for the combustion of the carbon and sulfur was in a separate package, in the molecule of potassium nitrate, and however finely the mixture was ground, some of the atoms, in the excitement of the explosion, failed to find their proper partners at the moment of dispersal. The new gunpowder besides being smokeless is ashless. There is no black sticky mass of potassium salts left to foul the gun barrel.