 The preceding theories represent the earliest stage of the insolubilia-literature. Although these theories are sometimes mentioned in the later literature, and in the case of “restriction” often accepted in the later literature, much more sophisticated treatments began to emerge in the second quarter of the fourteenth century. The turning point is Thomas Bradwardine, whose own theory was enormously influential on later authors. Shortly after Bradwardine, two other English authors from this middle period are also important: Roger Swyneshed  (Section 3.3),  and William Heytesbury  (Section 3.4).  A little later, important contributions were made by Parisian authors, Gregory of Rimini  (Section 3.7),  John Buridan  (Section 3.8)  and Albert of Saxony  (Section 3.9).