Yajnadatta, the Mad Man

"The Shurangama Sutra relates the story of Yajnadatta, the mad man of Shravasti, who one day looked in the mirror and noticed that the person reflected in it had a head. At that point, he lost his reason and said, 'How come that person has a head and I don't? Where has my head gone?' He then ran wildly through the streets asking everyone he met, 'Have you seen my head? Where has it gone?' He accosted everyone he met, yet no one knew what he was doing. 'He already has a head,' they said. 'What's he looking for another one for?'
There are a lot of people just like poor Yajnadatta."
-- Master Hsuan Hua

From Thus Have I Heard, edited by Minh Thanh and P.D. Leigh