A by-product of future research might lead to the transmutation of lead into gold. The possibility of this transformation of elements is subject to the same arguments as those above about the splitting up of the atom and the release of great quantities of energy. The path of decay from radium to lead lies clearly exposed even now, but it is very questionable whether mankind will finally have cause to offer up hymns of thanksgiving if this line from lead on to the precious metals should be continued, for it would cause our conception of the latter to be shattered. Gold made from lead would not give rise to an increase in the value of the meaner metal, but to the utter depreciation of gold, and hence the loss of the standard of value that has been valid since the beginning of our civilization. No economist would be possessed of a sufficiently far-sighted vision to be able to measure the consequences on the world's market of such a revolution in values. The chief product would, of course, be the gain in energy, and we must bear this in mind when we give ourselves up to our speculations, however optimistic or catastrophic they may be. The impenetrable barrier "impossible" no longer exists. Einstein's wonderful "Open Sesame," mass times the square of the velocity of light, is thundering at the portals. And mankind finds a new meaning in the old saw: One should never say _never_! CHAPTER III VALHALLA Order of Distinction and Characteristics of Great Discoverers.--Galilei and Newton.--Forerunners and Priority.--Science and Religion.--Inheritance of Talent.--A Dynasty of Scholars.--Alexander von Humboldt and Goethe.--Leonardo da Vinci.--Helmholtz.--Robert Mayer and Dühring.--Gauss and Riemann.--Max Planck.--Maxwell and Faraday. I HAD made up my mind to question Einstein about a number of famous men, not concerning mere facts of their lives and works, for these details were also procurable elsewhere, and, moreover, I was not ignorant of them, but what attracted me particularly was to try to discover how the greatness of one might be compared with that of another. This sometimes helps us to see a personality in a different light and from a new perspective, which leads us to assign to him a new position in the series of orders of merit.