## Finishing Proust, redux

Back in December 2006 I wrote about finishing Proust and made a rough argument about how often anyone on earth finishes the whole thing. The argument was a bit subtle. I was never 100% convinced it was sound, but no-one I showed it to found a hole in it. I still think about the question from time to time. The other day I mentioned the original post to Tim O’Reilly. Later that day, I realized there’s a much simpler way to get an estimate, with far fewer assumptions.

The new approach is simply to divide the number of hours that have passed since In Search of Lost Time was published by the number of people who’ve ever finished it. That average is a crude measure, but it may be nevertheless quite accurate and it’s irresistibly interesting to me to see how it compares to my original 2006 estimate of 2.19 hours.

So, assume 2B people were alive in 1927 when the final volume was published, and 6.4B alive at the end of 2006 (source).

Assume that no-one alive in 1927 was still alive in 2006 (obviously not the case, but not unreasonable and not a significant error). I.e., there were 4.4B births in those 79 years. Note: This is ignoring a significant number of people who were born after 1927 and who died before 2006. But it is including everyone born from 1990 onwards, essentially zero of whom would have read Proust by 2006.

In my original post I estimated that one person in 10K actually finishes the whole book. So that’s 4.4B/10K = 440K people who read the book during the 79 years.

79 years is 28,835 days, or 692,040 hours. Doing the division, 692,040 / 440,000 = 1.57 hours.

I.e., by the above rough reasoning, someone, somewhere on earth, finishes Proust every 1.57 hours, on average.

I find the closeness of the two estimates quite remarkable. There’s only one shared assumption (1 in 10,000 finishes). Both estimates are quite crude, yet there’s only about a 30% difference in the answers. I was expecting them to be much more divergent.