Viruses have been a plague on the human race forever. The common cold, of course, is the most familiar virus of them all, but even a cold can be deadly. Beethoven caught a cold when he was going to visit his mother on a freezing winter night, and he died. But there are at least five thousand more of these aggravating little monsters and, as we’ve seen, they keep changing and improving their ability to cause trouble. I can claim that I once played a tiny part in the eternal battle against viruses. Fifty years ago, as an impoverished graduate student, I spent two weeks as a paid volunteer at an establishment called The Cold Research Center near Salisbury in England. It was a perfect getaway, because we were human guinea pigs held in complete isolation for the duration of the experiments. They tested whether we could catch the virus by being wet or chilled, or by sitting in a draft, or even by having the live viruses inserted into our noses. To protect the integrity of the experiment and