Many of these ideas can be seen or at least hinted at in the Memento movie. One such idea is that of psychological continuity theory, which states that your identity is based on certain psychological characteristics that have existed continuously since a person's birth. In this theory, these characteristics can include memories, morals, values, conscience, and personality. Interestingly, using these criteria, I don't believe Leonard can be considered the same person throughout the entire film. Because Leonard does not have the ability to create new memories and does not retain the same morals, values, or personality as before the incident, it is difficult to use psychological continuity theory to justify that Leonard is the same person as before. The next theory that addresses this issue is the theory of physical continuity, which states that a person's identity is based on a body that has existed continuously from birth until today. I think that using this theory, we can demonstrate that Leonard is still the same person. Because Leonard has continuously possessed the same body since his birth, we can say, using the theory of physical continuity, that he is the same person as before birth.