Mad Money

I returned a passel of books to the library and took out another mickle of books. Suppose I picked up one book and after ten pages decided that it didn't fit my need at the moment? What if I didn't have another one to peruse?

What is there about library books that trumps the not-yet read books on my own bookshelf? And I like those books.

Having something to fall back on, something that means you won't be caught shorthanded--

My mother always suggested that I should always have mad money on me--not to spend, but to have if necessary.

"Tuck it in your wallet."

Books on my shelf are like mad money.