Assume that human embryonic stem-cell research will one day allow doctors to repair brain tissues that have been damaged by diseases like Alzheimer’s. Now imagine that such a wonder-cure became available to Ronald Reagan’s doctors, before Reagan’s biological death but after Alzheimer’s had damaged all the tissues of Reagan’s brain that supported his mental life. The doctors inject the relevant stem cells into his brain, the damaged tissues grow back intact, and the doctors guarantee that the personality traits at the end of the recovery are the same as those before the disease began its destructive course. Most proponents of embryonic stem-cell research would agree (1) that Reagan himself would survive each stage of this adventure, (2) that Reagan would retain his basic moral status during each stage of this adventure, and (3) that any accounts of personal identity or moral status that cannot accommodate (1) and (2) should be rejected. But the only plausible accounts of personal identity and moral status that accommodate (1) and (2) are accounts that entail that you and I were once human embryos with the same basic moral status that we have now. Therefore, proponents of embryonic stem-cell research should only support non-destructive versions of such research.