Essays on Infinite Lifespans   Russell Blackford 263 before we were even conceived (p8). [3] This assumes that each  of  us  is  the  biologically  organized  matter  continuous with a particular zygote, created at a particular point in time. Kaufman takes a different approach. He argues that even if the self, as a “metaphysical entity” (p309), [5] is defined in this way, the real problem for Lucretius is that events in my past affect my current personality. If I had been alive at the time of the Carthaginian wars, I would not now be as I now am, thinking the thoughts that I do and having the wishes that I have! That being so, Kaufman says, I cannot coherently regret not having been alive earlier, for I would be wishing away my own personality (307–311). [5] In my view, these arguments are not at all decisive against the position of Lucretius. The short answer to Kaufman is that his approach proves too much. Many events whose occurrence we later regret influence the development of our personalities. Indeed, Kaufman’s argument appears to rule out the appro- priateness of regret in those cases where it actually seems to be most appropriate, such as when someone’s personality has changed deeply over the years as a result of dwelling upon a crime, or some non-criminal but seriously hurtful act, that she once committed. The argument put by Nagel is both more difficult and more convincing. In the end, however, it appears to fail. Assume for the sake of argument that ‘I’ am a biologically organized four- dimensional being whose earliest temporal stage is the zygote that was formed when one of my father’s sperm cells fertilized one of my mother’s ova. It seems that I could not simultane- ously have an identity defined in such a way and have had experiences before I was even conceived. At  the  same  time,  we  can  imagine  logically  possible  sce- narios  in  which  the  very  same  zygote  could  have  come into  existence  at  an  earlier  time  than  it  did.  Imagine  that a  certain  person  was  born  twenty  years  after  a  particular