The Content and Purpose of Stephen’s Commentary
Around half of the Liber Mamonis consists of commentary added by Stephen. The insertions that have been identified so far include explanations that help to expound Ibn al-Haytham’s arguments. Stephen also adds genuine astronomical elements as well as digressions on subjects that Ibn al-Haytham does not address. Other comments in the Liber Mamonis can be summarised as programmatic or motivational statements. These are mostly, but not exclusively, found in Stephen’s prefaces to the four books into which he divided the text. In the same category one can also place Stephen’s criticism of outdated doctrines in European science. In the following, these and other elements of Stephen’s commentary and their function for the composition of the Liber Mamonis will be discussed.