20 February

Looking at old photos, it's tempting to think of history as something that happens in discrete slices of time. This one, for example, taken in the 19th century, can make you think about the 19th century as a slice of time that 19th century people lived in. Except...time doesn't work like that. In every time you have multiple generations. There are some people who only lived in the 19th century, but there are many more who lived in both the 18th and 19th, or the 19th and 20th. At any given time you have the full range of ages, and what that does is spread time out, so that there's continuity from one time to the next. That's how time looks like it's moving on, because the young of today will carry forward some of today into the world tomorrow, after we're gone. The idea of time 'passing' ignores what makes it pass - ageing, death and multiple generations of people coexisting.