" About two millenia ago, a Jewish sage, Hillel, said : 'If I do not do this job-who will do it ? And if I do not do this job right now-when shall I do it ? But if I carry it out only for my own sake-what am I ? ' The first two parts of this saying suggest that each man is unique and each man's life is singular; by the same token, no man can be replaced and no man's life can be repeated."