Stephen Ryan at MinistryValues.com relates a fascinating account from an article in the NYT dated 1905 that explains the photo above:
It had been arranged that when the humorist arose to speak Miss Angersten, a well-known model, was to appear in the garb and with the simple dignity of Jean d'Arc, his favorite character in all history. He was on his feet as Jean d'Arc entered the room. She wore the armor of the French heroine and her hair and face made a strangely appealing picture.
The face of the humorist, which had been wearing its "company" smile all night, suddenly changed. He had every appearance of a man who had seen a ghost. His eyes fairly started out of his head, and his hand gripped the edge of the table.
Jean d'Arc presented him with a wreath of bay. He merely bowed, with his eyes fixed on the girl's face. They followed her as in reverent silence she passed out, followed by a little boy in suitable costume, bearing a banner over her head. Then Mark Twain spoke. His voice was broken, and his word came slowly..More>>