Philoponus has raised the central question of the scientific and philosophical Aristotle's work on chemistry. The work called On Generation and Corruption examines the question of how is the mixture (chemical combination) possible? Philoponus’ contribution to the topic is in his new definition of potential, the third of the seven elements criteria. There are various interpretations of the theory of mixture, but it seems that Philoponus is rather refining Aristotle's approach than rejecting it. One of interpreters of Philophonus’ work on the theory of mixture, De Haas, implies that "no element can possess a quality essential to it except to a superlative extent".