To the Editor:

Nicholas Kristof’s column “An Idiot’s Guide to Inequality” (July 24) opens with a disturbing piece of information worthy of its own commentary — that Amazon keeps track of what passages readers highlight in their Kindle e-books. As he notes, this information is also a rough measure of how much of a book has been read — and indicates that most readers are not finishing Thomas Piketty’s book “Capital in the Twenty-First Century.”

I have several books on my shelves that have bookmarks stuck in spots where I just gave up or intended to return someday (I don’t highlight), but I am the only one who knows.

ALAN BECKOFF

Hollis Hills, Queens, July 24, 2014