This, I say, is a first impression and a natural one.  I hasten to add:  this should not be the last impression of those who read with thoughtful attention.

One thing should be emphasized at the outset:  nothing will so often bear rereading as the history of philosophy.  When we go over the ground after we have obtained a first acquaintance with the teachings of the different philosophers, we begin to realize that what we have in our hands is, in a sense, a connected whole.  We see that if Plato and Aristotle had not lived, we could not have had the philosophy which passed current in the Middle Ages and furnished a foundation for the teachings of the Church.  We realize that without this latter we could not have had Descartes, and without Descartes we could not have had Locke and Berkeley and Hume.  And had not these lived, we should not have had Kant and his successors.  Other philosophies we should undoubtedly have had, for the busy mind of man must produce something.  But whatever glimpses at the truth these men have vouchsafed us have been guaranteed by the order of development in which they have stood.  They could not independently have written the books that have come down to us.

This should be evident from what has been said earlier in this chapter and elsewhere in this book.  Let us bear in mind that a philosopher draws his material from two sources.  First of all, he has the experience of the mind and the world which is the common property of us all.  But it is, as we have seen, by no means easy to use this material.  It is vastly difficult to reflect.  It is fatally easy to misconceive what presents itself in our experience.  With the most earnest effort to describe what lies before us, we give a false description, and we mislead ourselves and others.

In the second place, the philosopher has the interpretations of experience which he has inherited from his predecessors.  The influence of these is enormous.  Each age has, to a large extent, its problems already formulated or half formulated for it.  Every man must have ancestors, of some sort, if he is to appear upon this earthly stage at all; and a wholly independent philosopher is as impossible a creature as an ancestorless man.  We have seen how Descartes (section 60) tried to repudiate his debt to the past, and how little successful he was in doing so.

Now, we make a mistake if we overlook the genius of the individual thinker.  The history of speculative thought has many times taken a turn which can only be accounted for by taking into consideration the genius for reflective thought possessed by some great mind.  In the crucible of such an intellect, old truths take on a new aspect, familiar facts acquire a new and a richer meaning.  But we also make a mistake if we fail to see in the writings of such a man one of the stages which has been reached in the gradual evolution of human thought, if we fail to realize that each philosophy is to a great extent the product of the past.