 Peter said you can't even make sense of some of his writing. His letters are weighty and strong, but his personal presence is unimpressive and his speech is contemptible. That's an obstacle if you're trying to be a communicator of God's word. But his fourth obstacle was one he couldn't do anything about as much as he tried. 2 Corinthians 12 verses 8 and 9 said he had a thorn in the flesh.