Galen’s commentary on Aristotle (in a way consistent with the approach considered in §3.5) involves not just explication but also addition. He claims that in his commentary on the Categories (again, unfortunately lost) he added an eleventh category to Aristotle’s ten: that of “composition”. In the context of Aristotelian syllogistic logic, meanwhile, there is some suggestion that he felt it necessary to posit a fourth figure in addition to the Aristotelian three. In fact, there seems considerable doubt concerning both the value of such a fourth figure and Galen’s authorship of it (Morison 2008: 85–91); a preferable interpretation may be that references to this “fourth syllogism” are not to a new categorization within the system of Aristotle’s simple syllogisms, but rather (more interestingly) to an original attempt at the analysis of compound syllogisms, which Galen apparently carried out with specific reference to certain arguments in Plato.