To a savage contemplating a railway train in motion, the engine would present itself as the master of the situation,--the determining cause of the motion and direction of the train. It visibly takes the lead, it looks big and important, and it makes a great noise. Even people a long way up in the scale of civilization are in the habit of taking these attributes, perhaps not as the essential ones of leadership, but at all events as those by which a leader may be recognized. Still that blustering machine, which puffs and snorts, and drags a vast multitude in its wake, is moving along a track determined by a man hidden away from the public gaze. A line of rail lies separated from an adjacent one, the pointsman moves a handle, and the foaming giant, that would, it may be, have sped on to his destruction and that of the passive crew who follow in his rear, is shunted to another line running in a different direction and to a more desirable goal. The great intellectual pointsman of our age--the man who has done more than any other of this generation to give direction to the thought of his contemporaries--has passed away; and we are left to measure the loss to humanity by the result of his labors. Mr. Mill's achievements in both branches of philosophy are such as to give him the foremost place in either. Whether we regard him as an expounder of the philosophy of mind or the philosophy of society, he is _facile princeps_. Still it is his work in mental science which will, in our opinion, be in future looked upon as his great contribution to the progress of thought. His work on political economy not only put into thorough repair the structure raised by Adam Smith, Malthus, and Ricardo, but raised it at least one story higher. His inestimable "System of Logic" was a revolution. It hardly needs, of course, to be said that he owed much to his predecessors,--that he borrowed from Whewell much of his classification, from Brown the chief lines of his theory of causation, from Sir John Herschel the main principles of the inductive methods. Those who think this a disparagement of his work must have very little conception of the mass of original thought that still remains to Mr. Mill's credit, the great critical power that could gather valuable truths from so many discordant sources, and the wonderful synthetic ability required to weld these and his own contributions into one organic whole.