 Hugh’s Didascalicon (itself inspired by previous classifications—see Weisheipl 1965) however only allows for Kilwardby to include the sciences in what is called knowledge—to this he must (and does) add the principles of the division of the different sciences into various fields of inquiry and then the classification of the different sciences within a certain field of inquiry. Kilwardby goes beyond Hugh and previous classifications not so much with regard to the principles of division and classification, but rather with regard to what is implied in science—that is to say, with regard to the necessary requirements for something to be considered scientific in a certain field of inquiry and process of discovery according to the Aristotelian deductive model of science. Any science (not  art)[30]  needs to fulfill three main requirements: first, it should have a subject matter (DOS 167; 221); second, it should present the parts and species of a science’s subject matter and their properties (DOS 650–652); third, it should take into account the first common principles of demonstration and have a set principles appropriated to its genus (NLP I.23).