"Buying books would be a good thing if one could also buy the time to read them in: but as a rule the purchase of books is mistaken for the appropriation of their contents"

Arthur Schopenhauer is suggesting that while buying books might look like a favorable thing, it is only really advantageous if the buyer likewise has the time to check out and take in the content within. Frequently, people buy books just to own them, without genuinely engaging with their concepts or principles. The act of purchasing a book is not the same as investing time in reading and comprehending it. Schopenhauer is alerting against the misconception that owning books suffices to gain knowledge and insight from them.