A blind man had been waiting a while at a busy road for someone to offer to guide him across, when he felt a tap on his shoulder.
“Excuse me,” said the tapper, “I’m blind – would you mind guiding me across the road?”The first blind man took the arm of the second blind man, and they both crossed the road.
Apparently this is a true story. The first blind man was the jazz pianist George Shearing. He is quoted (in Bartlett’s Anecdotes) as saying after the event, “What could I do? I took him across and it was the biggest thrill of my life.”