studies of others, and in the conduct of our own understanding; and it is chiefly on this slow, but continued accession to our stock of logical principles, arising from a systematical accumulation, at proper intervals of time, of individual contributions, that I rest my hopes of the farther advancement of that science in after ages. To speak, in the actual state of the world, of a complete system of logic (if by that word is meant anything different from the logic of the schools), betrays an inattention to the object at which it aims, and to the progressive career of the human mind; but, above all, it betrays an overweening estimate of the little which logicians have hitherto done, when compared with the magnitude of the task which they have left to their successors.

It was not, however, with a view to the advancement of Logic alone, that I was led to engage in these inquiries. My first and leading aim was to take as comprehensive a survey as possible of the human constitution, in order to shew how limited our common plans of education are, when compared with the manifold powers, both of intellect and of enjoyment, by which Nature has distinguished our species. The cultivation of Reason, with a view to the investigation of truth, is only one of the means, although one of the most essential means, towards the improve ment and happiness of the individual; and it is merely on account of its high comparative importance in this respect, that I so often recur to it in the prosecution of my undertaking. The two last Essays of this volume will, I hope, be useful in illustrating my general idea.

I have been insensibly led into a much longer detail than I intended about my future plans. I should be sorry if any of my readers should ascribe this prolixity to an idle egotism. Had I enjoyed a more unbroken leisure, my design would have been many years ago completed, as far as the measure of my abilities enabled me. I still look forward, though with hopes less sanguine than I once indulged, to the prosecution of my task; and if (as is more than probable) these hopes shall be disappointed, it will afford me some satisfaction to have left behind me this memorial, slight as it is, of what I had meditated.

I have only to repeat once more, before the close of this Dissertation, that the correction of one' single prejudice has often been attended with consequences more important and extensive than could be produced by any positive accession to the stock of our scientific information. Such is the condition of man, that a great part of a philosopher's life must necessarily be spent, not in enlarging the circle of his knowledge, but in unlearning the errors of the crowd, and the pretended wisdom of the schools; and that the most substantial benefit he can bestow on his fellow-creatures, as well as the noblest species of Power to which he can aspire, is to impart to others the lights he has struck out by his meditations, and to encourage human reason, by his example, to assert its liberty. To what did the discoveries made by Luther amount, but to a detection of the impostures of the Romish church,

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and of absurdities sanctioned by the authority of Aristotle? Yet, how vast the space which is filled by his name in the subsequent history of Europe! and how proud his rank among the benefactors of mankind! I am doubtful if Bacon himself did so much by the logical rules he gave for guiding the inquiries of his followers, as by the resolution with which he inspired them to abandon the beaten path of their predecessors, and to make excursions into regions untrodden before; or if any of his suggestions, concerning the plan of experimenting, can be compared in value to his classification and illustration of the various prejudices or idols which mislead us from the pure worship of Truth. If the ambition of Aristotle has been compared, in the vastness of its aim, and the plenitude of its success, (and who can say that it has been compared unjustly?) to that of his Royal Pupil who conquered the world; why undervalue the efforts of those who first raised the standard of revolt against his universal and undisputed despotism? Speedily after the death of Alexander, the Macedonian empire was dismembered among his principal officers. The empire founded by the philosopher continued one and undivided for the period of two thousand years; and, even at this day, fallen as it is from its former grandeur, a few faithful and devoted veterans, shut up in its remaining fortresses, still bid proud defiance, in their master's name, to all the arrayed strength of Human Reason. In consequence of this slow and gradual emancipation of the Mind, the means by which the final result has been accom

plished attract the notice only of the reflecting inquirer; resembling in their silent, but irresistible operation, the latent and imperceptible influence of the roots, which, by insinuating themselves into the crevices of an ancient edifice, prepare its infallible ruin ages before its fall; or that of the apparently inert moisture, which is concealed in the fissures of a rock, when enabled, by the expansive force of congelation, to rend asunder its mass, or to heave it from its basis.

As it is seldom, in such instances, easy to trace to particular individuals what has resulted from their exertions, with the same precision with which, in physics or mechanics, we refer to their respective inventors the steam-engine or the thunder-rod, it is not surprising, that the attention of the multitude should be so little attracted to the intellectual dominion of superior minds over the moral world ; but the observer must be blind indeed, who does not perceive the vastness of the scale on which speculative principles, both right and wrong, wrong, have operated upon the present condition of mankind; or who does not now feel and acknowledge how deeply the morals and the happiness of private life, as well as the order of political society, are involved in the final issue of the contest between true and false philosophy.

In selecting the subjects of the Essays contained in the First Part of this volume, I have had in view chiefly the correction of some mistaken opinions concerning the origin of our Knowledge (or, to

use the more common phraseology, concerning the origin of our Ideas), which, as they are naturally suggested by certain figurative modes of speaking, sanctioned by the highest authorities, are apt to warp the judgment in studying the most elementary principles of abstract science. I have touched slightly on the same question in one of the sections of my former work; where the doctrine maintained with respect to it coincides exactly with that which it is now my object to establish by a more ample discussion. At that time, I did not imagine that it differed so widely from the current maxims of the learned, as I have since found from various later publications; and accordingly (as the point in dispute is intimately connected with almost every other question relating to the Human Mind), I have availed myself of the present opportunity to throw upon it some additional light, before resuming my analysis of the Intellectual Powers. With this view, I have been led to canvass, pretty freely, the doctrines not only of my predecessors, but of several of my contemporaries; and to engage in various arguments, which, however unconnected they may appear in a table of contents, will be all found, upon examination, to bear upon the same conclusion. I flatter myself, therefore, that those who may take the trouble to follow the train of thought which has led me from one Essay to another, will discover, in this part of my book, a greater degree of unity than its titlepage seems at first to promise.

The Essays which fill up the rest of the volume have no necessary dependence on the disquisitions