 However, the distinction is not, it turns out, so clear-cut. Having begun to illustrate the distinction between inquiry if or whether something is and what it is with the question ‘whether there is or is not a centaur or a god’, he then characterizes the knowledge achieved as ‘knowing that it is’. And in the second chapter, he begins to link the two sequences of inquiry by means of his syllogistic concept of “middle term,” the term that is common to the two premises in a syllogistic proof.