You don't own the text, but you do own the manifestation of the text as a physical book. Sure the text doesn't magical stay with you after a fire burns down your house (like all other items in your house) and it isn't eternal (like all other things aren't) but as long as you don't damage the item you own, it has value: the text.

Weired argument to say that you don't own a thing because it can be damaged or fall apart. You own it even if it is damaged by the way. The paper shreds after the fire are still yours.