He was attracted from an early age to various art forms: theater, opera, movies, and the Oz novels of L. Frank Baum.
He was particularly interested in the writings of critic Gamaliel Bradford, who immersed himself in the life and works of an author and then wrote what he called a "psychography" about the writer.
A thinker of broad range, Wagenknecht wrote or edited books on Henry James, Marilyn Monroe, Lillian Gish, John Milton, Geoffrey Chaucer, Jenny Lind, and Theodore Roosevelt.
He favored the Jamesian well-made novel but made an effort to be open to other types of writing, such as stream-of-consciousness works.
as one of the many book reviewers who ought to lose his job for not perceiving the merits and importance of William Gaddis' first novel, The Recognitions.
"[5] Wagenknecht himself pointed out his debt to Bradford and Sainte-Beuve: He also produced an enormous amount of film criticism, much of it before the movies became a fashionable subject of academic attention.