As a set-off against the list of paradoxes cited from Plato, it would be easy to quote a still longer list of brilliant contributions to the cause of truth and right, to strike a balance between the two, and to show that there was a preponderance on the positive side sufficiently great to justify the favourable verdict of posterity. We believe, however, that such a method would be as misleading as it is superficial. Neither Plato nor any other thinker of the same calibre—if any other there be—should be estimated by a simple analysis of his opinions. We must go back to the underlying forces of which individual opinions are the resultant and the revelation. Every systematic synthesis represents certain profound intellectual tendencies, derived partly from previous philosophies, partly from the social environment, partly from the thinker’s own genius and character. Each of such tendencies may be salutary and necessary, according to the conditions under which it comes into play, and yet two or more of them may form a highly unstable and explosive compound. Nevertheless, it is in speculative combinations that they are preserved and developed with the greatest distinctness, and it is there that we must seek for them if we would understand the psychological history of our race. And this is why we began by intimating that the lines of our investigation may take us back over ground which has been already traversed, and forward into regions which cannot at present be completely surveyed.