Bach elaborates his messiah theme in two other best-selling books. As Jonathan can be likened to a messiah, Donald Shimoda, in Illusions: Adventures of a Reluctant Messiah (1977), is directly called that name, and Bach's wife, Leslie Parrish, in The Bridge Across Forever: A Love Story (1984) is a new kind of messiah, a "soul-mate."

Illusions depicts the messianic characteristics as they would appear in a barnstorming pilot. (Shimoda, for instance, speaks philosophically, and his windshield is always clean.) The book's style is much more polished than Jonathan Livingston Seagull's but Shimoda's language resembles Jonathan's as he says that all should be sons of God, who commands, "BE HAPPY."

While Jonathan is allegorical, Shimoda is a real friend of the narrator's seen in ultimate terms, and Leslie Parrish is portrayed as a cherished mate and savior. In both books, the perspective of Jonathan Livingston Seagull ("real" soul, illusory...