Who is Dr. Rhys from A String in the Harp and what is their importance?

Dr. Rhys is one of David's colleagues at the University. He is studying ancient Welsh literature and is especially interested in Taliesin. Rhys is described as a thin, little man, who wears a well-worn suit and wire-framed spectacles. Over the course of the novel, Dr. Rhys comes to believe Peter's stories and asserts that not everything in the world can be explained by science.