An "intrinsic property" is one whose possession by an object at a time involves nothing other than the object (and its parts) at that time; an "extrinsic property" is one whose possession at a time involves something else. We might say, therefore, that the properties of being red and round are intrinsic to this ball, but the properties of being in Rhode Island, being less than five feet away from a tree, and having once been owned by my sister are extrinsic to it.

Peter Geach has made a corresponding distinction among changes. There is change whenever "F(x) at time t" is true and "F(x) at time t′" is false. Socrates will change when he puts on weight; he will also change when he comes to be shorter than Theaetetus merely in virtue of Theaetetus's growth. Changes of the second...