Make a list of the indoor public places you can spend three hours without buying anything. It is a short list, and it is getting shorter.

The café wants a coffee an hour. The shop wants the obvious. The station wants you on a train. Even the places that appear free are usually a transaction with the price moved somewhere less visible — the mall's warmth is advertising, the free wifi is a mailing list.

The library wants nothing. You can sit in one all afternoon, read six things, take none of them home, speak to nobody, and leave. Nothing has been extracted. There is no version of the building that works better if you spend more.

This is so unusual that people struggle to describe why libraries matter and fall back on books, which is the least of it. You can get books elsewhere, often faster. What you cannot easily get elsewhere is a warm, quiet, unsupervised room that does not care whether you are a customer.

Mine is a 1930s branch with high windows, radiators that clank in January, and a noticeboard advertising a knitting group and a class on filling in benefits forms. On a weekday afternoon it holds a handful of students, two people using the computers for things that are clearly consequential, someone reading a newspaper on a stick, and an infant being read to with great expression in the corner.

None of those people are there for the same reason. That is the point. The building is load-bearing in a way that does not show up in a spreadsheet of visits, and it is defended, when it is defended at all, with arguments about literacy — as if the room itself were not the thing.