The concepts of "substance and attribute" are the focus of a group of philosophical problems that have their origins in Greek philosophy and in particular the philosophy of Aristotle. The concepts are, of course, familiar to prephilosophical common sense. Yet although we are acquainted with the distinction between things and their properties and are able to identify the same things among the changing appearances they manifest in time, these commonsense notions give rise to a group of philosophical problems when we come to scrutinize them. Thus we may wonder what it is that remains the same when, for example, we say that the car has new tires and lights and does not run as smoothly as it used to, but is still the same car; or when we say that although we could hardly recognize him, this man is the same one we went...