Impelled by his sense of responsibility, Salk became one of this century's greatest scientists and public servants, exhibiting until his final days in June 1995 at the age of 80 a formidable strength of purpose with which he approached his self-assigned challenges. To many he was a living legend: Indeed, few scientists in modern times have been more revered worldwide than he. Perhaps even more importantly, few scientists have had more faith or held higher hopes for the future of humankind than Salk, a view he based on decades of observing nature through science and "the human side of nature" through his own life experience.

       Humanity's ills

        In the course of his life, begun in 1914, Salk witnessed the growing belief that science, in light of its modern successes, would be the answer for much of humanity's ills. Salk's own contribution--development of the first successful poliomyelitis vaccine, which was announced on April 12, 1955--was itself a symbol that through science humankind could improve on nature and to a varying extent control it for human benefit.