In life, there is the before, and then there is the after. The world in certain situations suddenly becomes sharply cleaved. And when future historians (and yes, there will be future historians) write of COVID-19, they will write of the cleavage.

First, though, some science. Scientists use the R0, or sometimes called the R ought curve. The number for this virus is likely a 3. This means that for every person with the virus, that person will pass it on to three other people. These three people, in turn, will pass it on to three people each. It’s called exponential growth.