Life at the top is financially rewarding, spiritually draining, physically exhausting, and short.

Even if it's absurd to think you can change things, it's even more absurd to believe that it is foolish and unimportant to try.

I certainly think this is a new dimension.

This year, 1996, has been designated the 'Year of the Vaccine,' commemorating the 200th anniversary of Edward Jenner's vaccination of James Phipps with cowpox virus and subsequent challenge with smallpox virus. Insight into the nature of viruses, and how viruses interact with mammalian cells, has evolved since the turn of the century.

The need to deal with pathogens has driven the evolution of the vertebrate immune system, so it should not be surprising that experiments with infectious agents have often illuminated key elements of the underlying mechanisms.

Many key concepts concerning the nature of immunity have originated from the very practical need to control virus infections.