Nor can it be without its influence upon his judgment of the significance of a doctrine, when it becomes plain to him that this significance can scarcely be fully comprehended until the history of the doctrine is known. For example, he thinks of the mind as somehow in the body, as interacting with it, as a substance, and as immaterial. In the course of his reading it begins to dawn upon his consciousness that he has not thought all this out for himself; he has taken these notions from others, who in turn have had them from their predecessors. He begins to realize that he is not resting upon evidence independently found in his own experience, but has upon his hands a sheaf of opinions which are the echoes of old philosophies, and whose rise and development can be traced over the stretch of the centuries. Can he help asking himself, when he sees this, whether the opinions in question express the truth and the whole truth? Is he not forced to take the critical attitude toward them? And when he views the succession of systems which pass in review before him, noting how a truth may be dimly seen by one writer, denied by another, taken up again and made clearer by a third, and so on, how can he avoid the reflection that, as there was some error mixed with the truth presented in earlier systems, so there probably is some error in whatever may happen to be the form of doctrine generally received in his own time? The evolution of humanity is not yet at an end; men still struggle to see clearly, and fall short of the ideal; it must be a good thing to be freed from the dogmatic assumption of finality natural to the man of limited outlook. In studying the history of philosophy sympathetically we are not merely calling to our aid critics who possess the advantage of seeing things from a different point of view, but we are reminding ourselves that we, too, are human and fallible. 86. PHILOSOPHY AS POETRY, AND PHILOSOPHY AS SCIENCE.--The recognition of the truth that the problems of reflection do not admit of easy solution and that verification can scarcely be expected as it can in the fields of the special sciences, need not, even when it is brought home to us, as it is apt to be, by the study of the history of philosophy, lead us to believe that philosophies are like the fashions, a something gotten up to suit the taste of the day, and to be dismissed without regret as soon as that taste changes. Philosophy is sometimes compared with poetry. It is argued that each age must have its own poetry, even though it be inferior to that which it has inherited from the past. Just so, it is said, each age must have its own philosophy, and the philosophy of an earlier age will not satisfy its demands. The implication is that in dealing with philosophy we are not concerned with what is true or untrue in itself considered, but with what is satisfying to us or the reverse.