The Headless Man

Q: A headless man had a letter to write; It was read by a man who had lost his sight. The dumb repeated it word for word; And deaf was he who listened and heard. Solve this riddle.

A: The letter in question is the letter "O". It is zero. The man had nothing to write. The blind could read nothing. The person who was dumb could repeat nothing. The deaf man listened and heard nothing.