 In 1335, the Mertonian logician and philosopher of nature William Heytesbury wrote an important treatise entitled Rules for Solving Sophisms (Regulae solvendi  sophismata).[26]  The first of its six chapters is on insolubles. The Rules as a whole, and this first chapter in particular, were widely read and commented on, particularly in Italy in the late-fourteenth and fifteenth centuries (see, e.g.,  Section 4.4  below). Indeed, Heytesbury’s theory is a competitor to Bradwardine’s as the most influential theory of insolubles in the whole of the Middle  Ages.[27]