they singled out the manuscripts of Aristotle to be published. I will not say that they decided wrongly; yet neither can I contend (as I argued in the case of the Platonic dialogues) that the presumption is very powerful in favour of that Canon which their decision made legal. The case is much more open to argument, if any grounds against the decision can be urged. Andronikus put in, arranged, and published the treatises of Aristotle (or those which he regarded as composed by Aristotle) included in the library conveyed by Sylla to Rome. I have already observed, that among these treatises there were some, of which copies existed in the Alexandrine library (as represented by the Catalogue of Diogenes), but a still greater number which cannot be identified with the titles remaining of works there preserved. As to the works common to both libraries, we must remember that Andronikus introduced a classification of his own, analogous to the Enneads applied by Porphyry to the works of Plotinus, and to the Tetralogies adopted by Thrasyllus in regard to the Dialogues of Plato; so that even these works might not be distributed in the same partitions under each of the two arrangements. And this is what we actually see when we compare the Catalogue of Diogenes with _our_ Aristotle. Rhetoric, Ethics, Physics, Problems, &c., appear in both as titles or subjects, but distributed into a different number of books or sections in one and in the other; perhaps, indeed, the compositions are not always the same. Before I proceed to deal with the preserved works of Aristotle--those by which alone he is known to us, and was known to mediæval readers, I shall say a few words respecting the import of a distinction which has been much canvassed, conveyed in the word _exoteric_ and its opposite. This term, used on various occasions by Aristotle himself, has been also employed by many ancient critics, from Cicero downwards; while by mediæval and modern critics, it has not merely been employed, but also analysed and elucidated. According to Cicero (the earliest writer subsequent to Aristotle in whom we find the term), it designates one among two classes of works composed by Aristotle: _exoteric_ works were those composed in a popular style and intended for a large, indiscriminate circle of readers: being contrasted with other works of elaborated philosophical reasoning, which were not prepared for the public taste, but left in the condition of memorials for the instruction of a more select class of studious men. Two points are to be observed respecting Cicero's declaration. First, he applies it to the writings not of Aristotle exclusively, but also to those of Theophrastus, and even of succeeding Peripatetics; secondly, he applies it directly to such of their writings only as related to the discussion of the _Summum Bonum_.[36] Furthermore, Cicero describes the works which Aristotle called exoteric, as having _proems_ or introductory prefaces.[37]