The importance of going through books

Hm, finishing the title I realized there might be a slight chance you think I'm about to embark on a journey through economics (it is tax season where I live, true). 

I'm on a mission to declutter. In short: to throw out stuff. 
So I pulled down every single book from the shelf and created this sandcastle-type-pile of books on the floor. Decided which to keep (easy). Which to let go (not always as easy). Which aren't even mine (friends, expect a call). And which are waiting to be read. 

I always keep a pile of unread books waiting in line. Around 10 at a time. 
Turns out the real number is 40.
I was surprised by the number. Feels quite astounding (and I don't want to tell you how many were half-read and forgotten)

Then, there was one who carried another surprise. 

There, by the first page. 500 kronor (that's around 50 euros)
Chills. 

You see, it's one thing to find cash where you think you might have left it. An old purse. Between couch cushions. In a pocket. 
I did not expect this. 

So before you say goodbye to your old books: make sure you look through them.