R. Austin Freeman, The Mystery of 31 New Inn (1913)
“ Suddenly the identity of the man flashed into my mind and I exclaimed in astonishment: "It can't be that poor creature at Kennington, Mr. Graves?" "I think it can," replied Thorndyke, "and I think it is. But could you swear to the identity in a court of law?" "It is my firm conviction that the photograph is that of Mr. Graves. I would swear to that." "No man ought to swear to more," said Thorndyke. "Identification is always a matter of opinion or belief. The man who will swear unconditionally to identity from memory only is a man whose evidence should be discredited. ”
