I trust that the case in favour of removing the statements about the heart, from the list of the “errors of Aristotle” is now clear; and that the evidence proves, on the contrary, that they justify us in forming a very favourable estimate of the oldest anatomical investigations among the Greeks of which any sufficient record remains. But is Aristotle to be credited with the merit of having ascertained so much of the truth? This question will not appear superfluous to those who are acquainted with the extraordinary history of Aristotle’s works, or who adopt the conclusion of Aubert and Wimmer, that, of the ten books of the “Historia Animalium” which have come down to us, three are largely or entirely spurious, and that the others contain many interpolations by later writers. It so happens, however, that, apart from other reasons, there are satisfactory internal grounds for ascribing the account of the heart to a writer of the time at which Aristotle lived. For, within thirty years of his death, the anatomists of the Alexandrian school had thoroughly investigated the structure and the functions of the valves of the heart. During this time, the manuscripts of Aristotle were in the possession of Theophrastus; and no interpolator of later date would have shown that he was ignorant of the nature and significance of these important structures, by the brief and obscure allusion—“in its cavities there are tendons” (_A_). On the other hand, Polybus, whose account of the vascular system is quoted in the “Historia Animalium” was an elder contemporary of Aristotle. Hence, if any part of the work faithfully represents that which Aristotle taught, we may safely conclude that the description of the heart does so. Having granted this much, however, it is another question, whether Aristotle is to be regarded as the first discoverer of the facts which he has so well stated, or whether he, like other men, was the intellectual child of his time and simply carried on a step or two the work which had been commenced by others. On the subject of Aristotle’s significance as an original worker in biology extraordinarily divergent views have been put forward. If we are to adopt Cuvier’s estimate, Aristotle was simply a miracle:— “Avant Aristote la philosophie, entièrement spéculative, se perdait dans les abstractions dépourvues de fondement; la science n’existait pas. Il semble qu’elle soit sortie toute faite du cerveau d’Aristote comme Minerve, toute armée, du cerveau de Jupiter. Seul, en effet, sans antécédents, sans rien emprunter aux siècles qui l’avaient précédé, puisqu’ils n’avaient rien produit de solide, le disciple de Platon découvrit et démontra plus de vérités, executa plus de travaux scientifiques en un vie de soixante-deux ans, qu’après lui vingt siècles n’en ont pu faire,”[39] etc. etc.