ter of these compositions it is hardly necessary to speak. They are not only written with great clearness, force, and eloquence, but they evince a subtile perception and a strong grasp of the higher problems of modern scientific thought. Beyond doubt the French lead the world in the arts of lucid and attractive scientific exposition; and Papillon stands eminent among his countrymen in the display of this excellence. Although dealing with the most complex questions, and surveying the great phenomena of life on all sides, and especially in its dynamical aspects, yet there are a glow and a fascination in his pages which we do not hesitate to say are unsurpassed in modern scientific literature. Nor has the work lost aught of these impressive characteristics in its English dress. Papillon has passed prematurely away, but Mr. Macdonough has done justice to his memory by this brilliant reproduction of the Frenchman's work, by which a distant and foreign people will be able to appreciate his genius. Papillon's view as a thinker, and the spirit of his scientific studies, are so admirably presented in his brief preface, that we quote it in full:
"This volume contains a series of essays written and published at different times, some of a general character, and others more special, and all relating to the activity of natural forces, especially those of life. The mere bringing together of these fragments has presented an opportunity of completing a methodical and uniform whole, combining exactness in details with generality of doctrines, and distinctly tracing the precise aspect of each group of phenomena in the picture of the close and universal relations that bind the whole together. An exposition is thus offered under an elementary form, in language freed from technical dress, of the most essential truths established of late by physics, chemistry, and biology, regarding the mechanism of natural forces, and the arrangement and combination of the fundamental springs of being in the world, especially in the living world. I indulge the hope that such a work might meet a kindly welcome from minds, ever increasingly numerous, that regard science as the subject neither of idle curiosity nor of passing entertainment, but as the object of earnest sympathy and of serious examination. Such, at least, is the principal purpose of this book.
"It has another, also. The evident disposition of the present day is to repose infinite hopes on the natural sciences, and to expect unlimited benefits from them. I certainly shall not view this inclination as an illusion, and this volume sufficiently attests the high value I set upon all that can encourage and foster such feelings. But precisely because I am not suspected of enmity to those sciences, it has seemed to me the more necessary to indicate a fatal mistake accompanying those commendable sentiments; I mean the mistake of those who, after loudly praising the excellence of science, denounce the weakness and deny the authority of metaphysics.
"Now, my reader will come upon more than one page manifestly inspired by the conviction that science, properly so called, does not satiate the mind eager to know and to understand, and that therefore metaphysics holds a large and an authorized place in the activity of human thought. While I have retouched every thing in these essays which seemed to me, from an exclusively scientific point of view, susceptible of a higher degree of exactness and precision, I have, on the contrary, preserved with jealous care the literal tenor of all the pages expressly written under the influence of that conviction. And I have done so, not because of any peculiar value in those reflections, many of which are nothing more than a very imperfect representation of my way of seeing, but because those reflections were then made for the first time, with absolute spontaneousness, and without the slightest system or premeditation. The reader will thus be able to see how general ideas naturally emerge from deep and close contemplation of a group of various details, how forcible their unsought impression is; in other words, how surely thought, following orderly and regular evolution, without studied intention as without dogmatic aim, arrives at the loftiest philosophic certainties.
"The thinker who freely seeks for truth, continuously changes his position in his aspirations toward mind and the ideal. He deserts the regions of phenomena and concrete things, to rise to those of the absolute and eternal. The farther he withdraws from the former, which had at first absorbed all his attention, the more strikingly does the perspective in which he viewed them alter. At last, he discerns nothing else in them but spectres without substance, and delusive phantoms. And in the degree and extent of his drawing near to the eternal and the absolute, reality comes more surely
