Read the passage from The Pillow Book. "One day when the Emperor visited Her Majesty’s roms, we heard that he had taken along the lute called Mumyō and that some of the ladies-in-waiting were strumming it. We went to have a look, but no one was playing. One of our group toyed with the strings and asked what the instrument was called. ‘It’s far too insignificant to have a name,’ said the Empress. Hearing her reply, I was once more reminded what an admirable mistress I served.” What evidence suggests that the author of the passage is a credible source?