PHYSICS pere’) and ‘cease’ (‘desinere’) Kilvington and his colleagues oVered to expound such verbs in order to deal with such problems as whether there were Wrst and last moments of motion The common answer was that there were not: only a last moment before a motion began, and a Wrst moment after motion ceased Walter Burley wrote a whole treatise On the First and Last Instant, dividing up entities and processes of various kinds, some of which had a Wrst instant and no last instant, others no Wrst instant but a last instant, and so forth He also extended the notions of continuity and divisibility to changes in quality as well as in quantity His book On the Intension and Remission of Forms discussed the nature and measurement of continuous change in properties such as heat and colour Scholastic philosophers discussing the heating of bodies customarily took one of two positions On one view, when a body grew hotter, it was by the addition of an element of heat On another view, change in temperature was to be explained as an admixture of heat and cold Burley introduced a third alternative: he introduced the notion of degrees of heat, on a single scale which he called a ‘latitude’ Heat and cold were to be considered not two qualities, but a single quality At one end of the latitude would be maximum heat, and at the other end maximum cold He thus introduced our modern concept of temperature and laid the foundation for important developments in physics 188