Alan Jacobs:

The older I get, the more common this experience becomes: finding that I am simply unable to read essays and articles on certain topics. I may, out of a sense of duty, begin to read something on these topics, but almost immediately my eyes begin to wander, or to glaze over. I strive to refocus; I re-read the same few sentences; but before long my mind has wandered elsewhere. Eventually I give up.

Me too.