The first few lines of: Book I. The New Bases of the Physics of the Universe Chapter I. The Present Anarchy of Science... Every philosopher devoted to the study of subjects with rather vague outlines and uncertain conclusions, such as Psychology, Politics, or History, who had a few years ago to peruse a work on Physical Science, must have been struck by the clearness of the definitions, the exactness of the demonstrations, and the precision of the experiments. Everything was strictly linked together and interpreted. By the side of the most complicated phenomenon there always figured its explanation. If the same philosopher had the curiosity to look for the general principles on which these precise sciences were founded, he could not but be compelled to admire their marvellous simplicity and their imposing grandeur. Chemistry and mechanics had the indestructible atom for their foundation, physics the indestructible energy. Learned equations, produced either by experiment or by pure reasoning, united by rigid formulas the four fundamental elements of things-i.e. time, space, matter, and force. All the bodies in the universe, from the gigantic star describing its eternal revolutions in space down to the infinitesimal grain of dust which the wind seems to blow about at will, were subject to their laws. We were right to be proud of such a science, the fruit of centuries of effort. To it was due the unity and simplicity which everywhere reigned. A few minds enamoured of formulas thought it possible to simplify them further by taking into account only the mathematical relations between phenomena. These last appeared to them solely as manifestations of one great entity, viz.: energy. A few differential equations sufficed to explain all the facts discovered by observation. The principal researches of science consisted in discovering new formulas that from that moment became universal laws which nature was forced to obey. Before such important results, the philosopher bent low, and acknowledged that if but little certainty existed in the surroundings in which he lived, at least it could be found in the domain of pure science. How could he doubt it? Did he not notice that the majority of learned men were so sure of their demonstrations that not even the shadow of a doubt ever crossed their minds? Placed above the changing flux of things, above the chaos of unstable and contradictory opinions, they dwelt in that serene region of the absolute where all uncertainty vanishes and where shines the dazzling light of pure truth. Our great scientific theories are not all very ancient, since the cycle of precise experimental science hardly covers more than three centuries. This period, relatively so short, reveals two very distinct phases of evolution in the minds of scholars. The first is the period of confidence and certainty to which I have just referred. In face of the daily increase of discoveries, especially during the first half of last century, the philosophical and religious dogmas on which our conception of the universe had for so long been based, faded and vanished completely. No complaint was raised. Were not absolute truths to replace the former uncertainties of ancient beliefs? The founders of each new science imagined that they had once for all built up for that science a framework which only needed filling in. This scientific edifice once built up, it would alone remain standing on the ruins of the vain imaginings and illusions of the past. The scientific creed was complete. No doubt it presented nature as regardless of mankind and the heavens as tenantless; but it was hoped to repeople the latter at an early date and to set up for our adoration new idols, somewhat wooden perhaps, but which at least would never play us false.