I'm finding this ''40,000 books'' thing mildly interesting.
For example;
40,000 books would weigh about 10 metric tons. Where would you put them?
How would anyone amass that amount of books? If you started when you were 10, and lived till 80, you'd have to buy 570 books a year.
Why would anyone own more books than it's humanly possible to read in 3-4 lifetimes?
I think he means 4,000.