  Philip does not interpret his organizing principle of the good in an unduly narrow or restrictive manner. Among the goods of nature he considers not to be diminishable by evil are time and eternity. After a discussion of whether good and evil are contraries and whether evil can be a principle or a genus, Philip launches into a discussion of whether the world is eternal and follows that by a comparison of time and eternity. The topic of eternity is one of some importance and was much discussed in the Middle Ages. Medieval philosophers in the Christian tradition to which Philip belonged believed that the world was created ex nihilo by God with a beginning and at some point in time will end. It soon became apparent that the newly rediscovered Aristotle did not share this commitment as he famously argues that the world is eternal. Thus, this was an issue that medieval philosophers needed to address.