We've all done it: stood in a library, looking around, we've been confronted by the fact that there are way, way too many books in existence for us to ever read. But when in history did that happen?
Randall Munroe has tried to answer that question over on his What If? site. Sadly, it's not an easy problem to solve, but he's had a good try:
The average person can read at 200-300 words per minute. If the average living writer, over their entire lifetime, falls somewhere between Isaac Asimov and Harper Lee, they might produce 0.05 words per minute over their entire lifetime. If you were to read for 16 hours a day at 300 words per minute, you could keep up with a world containing an average population of 100,000 living Harper Lees or 400 living Isaac Asimovs.
If we estimate that during their active periods, writers are producing somewhere between 0.1 and 1 word per minute, then one dedicated reader might be able to keep up with a population of about 500 or 1000 active writers. The answer... -- the date at which there were too many English books to read in a lifetime -- happened sometime before the population of active English writers reached a few hundred. At that point, catching up became impossible.
Which at least means that, while realising there's too much to read can feel a little depressing, you're far from the first to have to deal with it. [What If?]