[jonny_eh]

Ever pick up a book and wonder if you've already read it?

[driggs]

If you can't remember whether you've read it or not, then you've forgotten it, and having it on a list serves no purpose other than to "keep score".

You may as well read it again and hope it sticks this time!

[jonny_eh]

If you read it, and forgot it, maybe it's not worth reading again and knowing that you can save some time!