Who is Count Keyserling from Journey to the East and what is their importance?

Count Keyserling was a wealthy German philosopher, who traveled around the world and wrote about his journeys. H.H. suggests that Keyserling is not a member of the League, although he is widely considered by those outside of the League to be one. H.H. also believes that Keyserling's accounts have nothing to do with the Journey to the East.