History has preserved the record of the numerous attempts that have been made to form a rational conception of the whole world of phenomena, and to recognize in the universe the action of one sole active force by which matter is penetrated, transformed, and animated. These attempts are traced in classical antiquity in those treatises on the principles of things which emanated from the Ionian school, and in which all the phenomena of nature were subjected to hazardous speculations, based upon a small number of observations. By degrees, as the influence of great historical events has favored the development of every branch of science supported by observation, that ardor has cooled which formerly led men to seek the essential nature and connection of things by ideal construction and in purely rational principles. In recent times, the mathematical portion of natural philosophy has been most remarkably and admirably enlarged. The method and the instrument (analysis) have been simultaneously perfected. That which has been acquired by means so different -- by the ingenious application of atomic suppositions, by the more general and intimate study of phenomena, and by the improved construction of new apparatus -- is the common property of mankind, and shouldnot, in our opinion, now, more than in ancient times, be withdrawn from the free exercise of speculative thought. It can not be denied that in this process of thought, the results of experience have had to contend with many disadvantages; we must not, therefore, be surprised if, in the perpetual vicissitude of theoretical views, as is ingeniously expressed by the author of 'Giordano Bruno', "most men see nothing in philosophy but a succession of passing meteors, while even the grander forms in which she has revealed herself share the fate of comets, bodies that do not rank in popular opinion among the eternal and permanent works of nature, p 78 but are regarded as mere fugitive apparitions of igncor vapor." [Footnote] *Schelling's Bruno, 'eber das Gottliche und Naturaliche Princip. der Dinge', 181 (Bruno, on the 'Divine and Natural Principle of Things')