2 Corinthians 10:4-5, 10

(for the weapons of our warfare are not carnal, but mighty through God to the pulling down of strong holds;) casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ

For his letters, say they, are weighty and powerful; but his bodily presence is weak, and his speech contemptible.