A System demands consistency, but one might well ask whether two volumes written seven years apart can be consistent with each other. If the systematic structure of the content is unchanged, they can be, even though the solutions to the special problems may differ. The may criticism that have come and the new thoughts that have been developed in the interval have not changed the basic structure of the system. But they have certainly influenced the form and content in many respects. If the theological system were deductive, like a system in mathematics in which one assertion is derived from the other with rational necessity, changes in conception of thought would be damaging to the whole.