Questions about personal identity and about time affect us all. The concern for «our» future and the fear of «our» death are based on (mostly vague) concepts of personal identity over time. Though the atomic components of our present body are not identical with the ones shown on our childhood photos, we have no doubts in recognizing ourselves on those pictures. Similarly, we are convinced that «we» will be able to recognize «ourselves» on our present passport-photos even in the future. Is this confidence justified? If it is not, our conception of life and death would be as faulty as was the image of the universe in the Middle Ages.