[19] The subject is well discussed by W. Ogle in the introduction to his _Aristotle on the Parts of Animals_, London, 1882. When we turn to the Aristotelian biological works themselves we naturally inquire first into the question of genuineness, and here a difficulty arises in that all his extant works have come down to us in a state that is not comparable to those of any other great writer. Among the ancients admiration was expressed for Aristotle’s eloquence and literary powers, but, in the material that we have here to consider, very little trace of these qualities can be detected by even the most lenient judge. The arrangement of the subject-matter is far from perfect even if we allow for the gaps and disturbances caused by their passage through many hands. Moreover, there is much repetition and often irrelevant digression, while the language is usually plain to baldness and very frequently obscure. We find sometimes the lightening touch of humour, but the style hardly ever rises to beauty. Furthermore, even in matters of fact, while many observations exhibit wonderful insight and, forestalling modern discovery, betray a most searching and careful application of scientific methods, yet elsewhere we find errors that are childish and could have been avoided by the merest tyro. This curious state of the Aristotelian writings has given rise to much discussion among scholars and to explain it there has been developed what is known as the ‘notebook theory’. It is supposed that the bases of the material that we possess were notebooks put together by Aristotle himself for his own use, probably while lecturing. These passed, it is believed, into the hands of certain of his pupils and were perhaps in places incomprehensible as they stood. Such pupils, after the master’s death, filled out the notebooks either from the memory of his teaching or from their own knowledge—or ignorance. Thus modified, however, they were still not prepared for publication, even in the limited sense in which works may be said to have been published in those days, but they formed again the fuller bases of notes for lectures delivered by his successors. In this form they have finally survived to our time, suffering, however, from certain further losses and displacements on a larger scale. Some of the ‘Aristotelian’ works are undoubtedly more deeply spurious, but the works that are regarded as ‘genuine’ do not seem to have been seriously tampered with, except by mere scribal or bookbinders’ blunders, at any date later than a generation or two following Aristotle’s own time. These notebooks as they stand are in fact probably in much the state in which we should find them were we able to retrieve a copy dating from the first or second century B. C.[20] [20] The problem of genuineness is discussed in detail by R. Shute, _On the history of the process by which the Aristotelian writings arrived at their present form_, Oxford, 1888.