lv PREFACE BY THE AUTHOR. 
rious examination. Such, at least, is the principal pur- 
pose 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 illu- 
sion, and this volume sufficiently attests the high value 
I set upon all that can encourage and foster such feel- 
ings. But precisely because I am not suspected of en- 
mity 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 author- 
ity 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 metaphys- 
ics 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 
passages 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 
