We have reached two conclusions that are vital here: (1) that the metaphysical way of looking at the world involves a transformation of the world of physical science; (2) that it is the same world that lies open to both science and metaphysics. Out of this arises the problem of the _correlation_ of the two views; the two interpretations of the world. If science be right in conceiving the world under such categories as quantity and natural causation; if science be right in seeking a mechanical explanation of phenomena (that is, one that excludes prevision, purpose, and aim); and if metaphysics be right in refusing to accept this explanation as final and in insisting that the principle of ultimate interpretation is teleological, that it falls under the categories of prevision, purpose, and aim; then it is clear that the problem of correlation is on our hands. In dealing with this problem, it will be convenient to separate it into two questions: (1) that of the fact; (2) that of its rationale. The fact of the correlation is a thing of common experience. We have but to consider the way in which this Congress of Science has been brought about in order to have an exhibition of the method of correlation. Originating first in the sphere of thought and purpose, the design has been actualized through the operation of mechanical agencies which it has somehow contributed to liberate. On the scale of individual experience we have the classic instance of the arm moving through space in obedience to a hidden will. There can be no question as to the fact and the great difficulty of metaphysics does not arise in the task of generalizing the fact and conceiving the world as a system of thought-purposes working out into forms of the actual through mechanical agencies. This generalization somehow lies at the foundation of all metaphysical faith, and, this being the case, the real task here, aside from the profounder question of the _rationale_, is that of exhibiting the actual points of correlation; those points in the various stages of the sciences from physics to ethics and religion, at which the last category or result of science is found to hold as its immediate implication some first term of the more ultimate construction of metaphysics. The working out of this task is of the utmost importance, inasmuch as it makes clear to both the man of science and the metaphysician the intrinsic necessity of the correlation. It is a task analogous to the Kantian deduction of the categories. IV QUESTIONS OF THE ULTIMATE NATURE OF REALITY