This book is not intended for philosophers by profession, who will find nothing in it that has not been already set forth in other writings of the same author. It ought to be intelligible to all readers who are able generally to understand a book at all. To those who only wish to repeat, in somewhat varied order, certain phrases which they have already learned by rote, and who mistake this business of the memory for understanding, it will probably be found unintelligible. It ought to attract and animate the reader, and to elevate him above the world of sense, to a transcendental region; -- at least the author is conscious that he has not entered upon his task without such inspiration. Often, indeed, the fire with which we commence an undertaking disappears during the toil of execution; and thus, at the conclusion of a work, we are in danger of doing ourselves injustice upon this point. In short, whether the author has succeeded in attaining his object or not, can only be determined by the effect which the work shall produce on the readers to whom it is addressed, -- and in this the author has no voice.