  This is the positive side of Regius’ account of explanation.  The negative side, as with Descartes, is a rejection of forms and qualities as understood by scholastic philosophers. For example, Regius had argued in 1641 that one does not explain how the heart works by introducing a ‘sentient and vegetative soul.’ He commented: “That is saying nothing more than this: that the heart is moved by whatever is the principle by which we live, sense and move (for that is how the soul is defined), which begs the question as to what that is” (Regius 1641b, Disputatio VI, Corollary, par. V). Such an explanation of the heart’s motion is similar to explaining the motion of a clock by ‘a faculty of a certain kind.’ Regius proposed instead that we think of the world as a great machine, and that we explain natural phenomena by hypothesizing how that machine works.