Sir Arthur Stanley Eddington (1882-1944), not otherwise noted for his modesty, taught at Cambridge University and directed the observatory there. Eddington was an enthusiastic promoter of Einstein's theory of relatively, when it was still new to the scientific community.
Once a question was posed to him that ran thus:
"Is it true, Professor, that you are one of the three people in the world who understand Einstein's theory of relativity?"
Eddington hesitated, pondering the question with considerable thought.
"I'm sorry," began the interviewer. "I should have realized that a man of your intellectual honesty might find that question embarrassing."
"Not at all," replied Eddington. "I was simply trying to think who the third might be ..."