ORIGINS OF THE PROBLEM OF UNITY OF FORM 127 



imposdbilis.^ Yet, since at the earliest stage the question was 

 not discussed under this aspect, we are still far from knowing 

 how and when the Schoolmen became aware of the problem. 



We get nearer with Avicenna, who, according to the Errores 

 'philoso'phorum, explicitly maintained that est una tantum 

 forma suhstantialis in coinpodto. As a matter of fact, this 

 thesis stands at the head in the enumeration of Avicenna's 

 errors. Indeed, in his Metaphysics, section II, in the chapter 

 ' On the division of corporeal substance,' Avicenna holds that 

 the form of the genus is not made specific through anything 

 extrinsic. By this he implies that the form of the species is 

 not some essence besides the essence of the form of the genus. ^ 

 This is a clear statement of the unity thesis. Elsewhere too, 

 as for instance, in the Sufficieiitia, Avicenna firmly expresses the 

 same view: one and the same substantial form makes matter a 

 definite kind of body and a body: Non est alia jorma qua ignis 

 est ignis et qua est corpus.^ 



None the less, the weight of these arguments was felt only 

 at a later and more developed period of the debate. At all 

 events, we can trace its very beginning to Avicenna's Liher 

 sextus naturaliuTn, or De anima, translated into Latin at 

 Toledo in the second half of the twelfth century by Dominic 

 Gundissalinus and his associates, who also rendered into Latin 

 Algazel and Ibn Gebirol's Pons vitae. Avicenna argues from 

 the unity of the human soul to its substantiality. Since it is 

 the soul that makes man what he is and constitutes him in his 

 species, if there were in man diverse souls, man would be in 

 diverse species.^ Moreover, he posits unequivocally that the 



' Cf. among others, St. Thomas Aquinas, De s'piritualihus creaturis, a. 3 (ed. 

 L. W. Keeler, Romae: Gregorianum, 1938, p. 42) . 



' " 1 . Avicenna autem similiter videtur errasse ponens unam formam in com- 

 posite, ut patet in Il° tractatu Metaphysicae suae, capitulo * De divisione sub- 

 stantiae corporeae ' (ed. Venetiis, 1508, fol. 76ra) , ubi vult quod forma generis non 

 specificetur per aliquod extrinsecum. Per quod innuitur quod forma speciei non sit 

 aliqua essentia praeter essentiam formae generis." Ibid., pp. 24-26. Summa: "1. 

 Quod est tantum una forma substantialis in composito." p. 34. 



^ Avicenna, Sufficientia, II, c. 3. 



' " Anima ergo perfectio est subiecti quod est constitutus ab ea. Est etiam 



