T he problem which I wish to discuss can be in troduced by the following presum ptuous exercise in imagination. Let us imagine ourselves in the position of Leibniz's God. In His infinite understanding, He has a perfect knowledge of infinitely many possible worlds, each of them completely determ inate (presumably in infinite detail). One of them is the single world on which He has conferred actuality: the actual world. But what is it that He has conferred on that world in actualizing it? W hat does that world have by virtue of being actual that the o ther possible worlds do not have? In what does the actuality of the actual world consist?