The time, therefore, seems to have come, when every philosophic thinker not only ought to form, but may usefully express, a judgment respecting this intellectual movement; endeavouring to understand what it is, whether it is essentially a wholesome movement, and if so, what is to be accepted and what rejected of the direction given to it by its most important movers. There cannot be a more appropriate mode of discussing these points than in the form of a critical examination of the philosophy of Auguste Comte; for which the appearance of a new edition of his fundamental treatise, with a preface by the most eminent, in every point of view, of his professed disciples, M. Littre, affords a good opportunity. The name of M. Comte is more identified than any other with this mode of thought. He is the first who has attempted its complete systematization, and the scientific extension of it to all objects of human knowledge. And in doing this he has displayed a quantity and quality of mental power, and achieved an amount of success, which have not only won but retained the high admiration of thinkers as radically and strenuously opposed as it is possible to be, to nearly the whole of his later tendencies, and to many of his earlier opinions. It would have been a mistake had such thinkers busied themselves in the first instance with drawing attention to what they regarded as errors in his great work. Until it had taken the place in the world of thought which belonged to it, the important matter was not to criticise it, but to help in making it known. To have put those who neither knew nor were capable of appreciating the greatness of the book, in possession of its vulnerable points, would have indefinitely retarded its progress to a just estimation, and was not needful for guarding against any serious inconvenience. While a writer has few readers, and no influence except on independent thinkers, the only thing worth considering in him is what he can teach us: if there be anything in which he is less wise than we are already, it may be left unnoticed until the time comes when his errors can do harm. But the high place which M. Comte has now assumed among European thinkers, and the increasing influence of his principal work, while they make it a more hopeful task than before to impress and enforce the strong points of his philosophy, have rendered it, for the first time, not inopportune to discuss his mistakes. Whatever errors he may have fallen into are now in a position to be injurious, while the free exposure of them can no longer be so. We propose, then, to pass in review the main principles of M. Comte's philosophy; commencing with the great treatise by which, in this country, he is chiefly known, and postponing consideration of the writings of the last ten years of his life, except for the occasional illustration of detached points.