Who is Arthur Garvey Ulm from God Bless You, Mr. Rosewater, or, Pearls Before Swine and what is their importance?

Arthur Garvey Ulm is a poet who Eliot meets at a party. He gives the man a check and tells him to write about the truth. Eliot doesn't even remember his name at the time. Fourteen years later, Ulm sends him a book that he wrote that is soon to be published. He reminds Eliot of the check and the advice.