Comment by conanite

Another claim seems to be that a collection of unread books serves as a personal reminder of ignorance, that the un-known always exceeds the known, a kind of "memento ignorantiae" that gives us the humility and motivation to always seek to learn more rather than remain complacently content with the knowledge we have already acquired.

And possibly the physicality of a dead-tree library carries this effect more forcibly than an online shopping list.

Pardon my latin.