34. The definition of philosophy thus expresses the bond of union which unites the different systems, and serves as a clue by which the progress of the historian may be directed. The historian may sometimes lose sight of this clue, at other times he may perceive it very indistinctly, but in general he will be able to trace it as a fine thread running through and binding together the different systems which come under his inspection. The clue, in short, on which he must fix his eye, is the circumstance, that the truth which philosophical systems aim at is absolute, and not relative, truth; that is to say, is truth as it exists for all, and not truth as it exists merely for some, intelligence.
35. The difficulty of following out this principle must be confessed to be great; and this difficulty arises mainly from the fact that the philosophers whose system we have to examine and estimate, never distinctly realised, or held clearly before their minds, that conception of philosophy which is expressed in our definition. Hence they frequently appear to be engaged in researches which have little or no connection with that pursuit which we have defined as the proper vocation of philosophy. They frequently appear to reach results which fall very far short of the absolute truth, results very different from those which we might expect philosophers to place before us. They frequently appear to entertain the most wayward and capricious opinions, instead of being
