Viruses have always been with us.

Of our shared history with viruses, we recall only the tragic side: the best-known viruses are serial killers responsible for murderous epidemics. We feel a certain fear for them, mixed with admiration. In fact, they are biological entitites of disarming simplicity when it comes to their incredible capacity for adaptation... Gradually, the brighter side of the story comes to light: viruses are at the frontier between the living and the inert. They are part of our genetic heritage, and play a major role in our evolution.