 William of Sherwood (Guilelmus, Willelmus, Schyrwode, Shirwode, Shyreswode, and others) was a 13th century English logician who taught at the University of Paris and who worked in the Realist tradition of logic. His Introduction to Logic, written in the middle of the century, was one of the four most influential textbooks on logics in the 13th century, along with Lambert of Auxerre’s Summary, Roger Bacon’s Art and Science of Logic, and Peter of Spain’s Summaries of Logic. Roger Bacon in his Opus tertium (1267) singles Sherwood out for high praise, describing him as “much wiser than Albert [the Great]; for in philosophia communis no one is greater than he” (Kretzmann 1966, pp. 5–6; Kretzmann 1968, pp. 3–4).