Achillini of Bologna (1463-1512)
Eminent in the history of the science, and more distinguished than any of this age in the history of cerebral anatomy, Achillini of Bologna, the pupil and commentator of Mondino, appeared at the close of the 15th century. Though a follower of the Arabian school, the assiduity with which he cultivated anatomy has rescued his name from the inglorious obscurity in which the Arabian doctors have in general slumbered.
He is known in the history of anatomical discovery as the first who described the two tympanal bones, termed malleus and incus. In 1503 he showed that the tarsus consists of seven bones; he rediscovered the fornix and the infundibulum; and he was fortunate enough to observe the course of the cerebral cavities into the inferior cornua, and to remark peculiarities to which the anatomists of a future age did not advert. He mentions the orifices of the ducts, afterwards described by Thomas Wharton (1610-1673). He knew the ileo-caecal valve; and his description of the duodenum, ileum and colon shows that he was better acquainted with the site and disposition of these bowels than any of his predecessors or contemporaries.
Achillini studied medicine and philosophy in Bologna, and lectured in Bologna and Padua. He was Pomponazzi's chief opponent. He was regarded as a faithful proclaimer of the doctrine of Averroes and Siger de Brabant, although in fact he made made his own modifications to this doctrine.
The basic difference between the orthodox Averroistic doctrine and the views of Achillini concern the unity of the intellect, the object of knowledge, the theory of the concept, the theory of the double truth, and the relation between detailed natural science and metaphysics.
In Quodlibeta de Intelligentiis(1494), he defended the unity of the intellect and introduced the categories of virtus and anima cogitativa as pertaining to the intellect. Virtus designates a principle of unity and indestructibility, and anima cogitativa designates a principle of plurality and destructability. One consequence of his approach was that he distinguished two objects of knowledge: the universale — the object of the intellect, and the singulare — the object of the senses. In the question of the universals, Achillini wanted to connect the Aristotelian requirement that the universal must be contained in the singular with the need to save the purity and concreteness of the universale in the act of the intellect. This led to the ambiguous formula: "[universale est] singulare, singularitate universali non multiplicabili".
In his works Quaestio de potestate syllogismi and De distinctionibus(1510) he showed his talent in formal logic. In the question of the double truth, Achillini took the position of dimittere theologis (pardon the theologians), since the relation between Aristotelian-Averroistic doctrine and the Christian faith brought about many serious difficulties in theology. Achillini also defended Averroistic astronomy and Aristotelian physics. He also presupposed an hierarchy of knowledge: natural knowledge of the particular requires a metaphysical integration that will give a certain visio sub specie aeterni of nature (a vision of nature under the form of eternity). In his anatomical works (De humani corporis anatomia, 1516 and Adnotationes anatomicae, 1520) he emphasized the value of empirical factors but was not able to overcome the influence of the ancient anatomy which he thought to be unrivalled.
His students included Panfilo Monti, Ludovico Boccadiferro and Bacilieri.