 Wyclif explains the notion of formal distinction (or difference) in the Purgans errores circa universalia in communi (chap. 4, p. 38) and in the later Tractatus de universalibus. (On Wyclif’s formulation of the formal distinction see Spade 1985, pp. xx-xxxi, and Conti 1997, pp. 158–63.) The two versions differ from each other on some important points, and are both unsatisfactory, since Wyclif’s definitions of the different types of distinction are rather ambiguous.