During the winter of 412 to 411 BC, the Greek city of Parenthos, a port on the Sea of Marmara,

experienced a wave of illness.

Hundreds of Perinthians fell ill, with high fevers, coughing, sore throats, aches, and in some cases more severe symptoms.

We know this because a physician recorded these facts, and his record of the incident survives to our time.

The so-called cough of parenthus is historically significant for three reasons. First, the physician who

recorded the event was Hippocrates, one of the greatest names in the history of medicine.

Second, Hippocrates used the word epidemic to describe the event, a term that literally means on the people. It was already in use

in the Greek language, applied to various phenomena, but Hippocrates was the first to use it to describe

the outbreak of a disease, this one. And we primarily use the word in this Hippocratic sense

in our time.

Third, although we cannot say with certainty, this epidemic just might have been,

might have been, the first recorded outbreak of the disease we know today as influenza. Welcome to the history of the disease we know today as influenza.

Welcome to the history of the 20th century.

The 20th century. Episode 171.

Pale Horse, Pale rider, part one.

A virus is a peculiar thing.

It is nothing more than a very large and complex molecule.

Your body and mine are structures built from an assortment of very large and complex molecule. Your body and mine are structures built from an assortment of very large

and complex molecules, some of which are larger and more complex than a virus. But a virus is a

particular kind of molecule with some very strange properties. For example, it can collect material from its environment and use this material

to build a protective coating of proteins around itself, called a capsid. Now, I have to be

careful about my language here. Verbs like collect and build imply action, will, intention.

...