 Despite that, problems about identity appear to play a central role in a large number of philosophical issues whose discussion dates back to the ancient world. One of the most venerable concerns identity and change. Things change, but remain the same. The same poker is at one time hot, another time cold. How can something be both identical and different from one time to another? At first sight this problem evaporates once we draw the time honored distinction between numerical and qualitative identity. To say that a and b are qualitatively identical is to say that a exactly resembles b. To say that a and b are numerically identical is, at least, to say a and b are one thing and not two. Whether a and b can have all their qualities in common without being numerically identical is controversial. Nevertheless, it seems that a and b can be numerically identical without being qualitatively identical by having different qualities at different times.