138 DANIEL A. CALLUS 



and others '« in support of the unity thesis, and by the plural- 

 ists for their embryo-genesis theory.^** Medieval thinkers would 

 make their approach from various standpoints. Arguments 

 were drawn from the most disparate sources; a simile, an obiter 

 dictum frequently offered ample matter for speculation. What 

 might seem to us quite an insignificant, tentative suggestion 

 sometimes gave rise to long and important controversies. It is, 

 therefore, not surprising that there were indeed other factors 

 which mingled with these to strengthen the development and 

 growth of the problem. 



The next question with which we are confronted is when did 

 the problem itself reach the Universities of Paris and Oxford.^ 



Although it is beyond doubt that the problem was discussed 

 in the schools in the first decades of the thirteenth century, at 

 the latest, it would surely be rash, in our fragmentary knowl- 

 edge of this period, to assert definitely who were the first 

 masters to introduce it. 



It is rather disappointing that Daniel of Morley makes no 

 allusion to it in his Pliilosophia.'^° In one so familiar with 

 Avicenna and Arabic learning, we should expect to find an 

 echo of the discussions held at Toledo on psychological mat- 



potentias diversa vocabula sortitur ' [c. 13, PL 40, 788-9]." La Summa De Anima 

 di Frate Giovanni della Rochelle, ed. T. Domenichelli (Prato, 1882) , p. 138. Cf. 

 also Richard Rufus of Cornwall, for whom see D. A. Callus, " Two early Oxford 

 Masters on the Problem of Plurality of Forms: Adam of Buckfield — Richard 

 Rufus of Cornwall," Revue neoscolastique de Philosophic, XLII (1939), 439. 



"* Albertus Magnus, Summa de creaturis, II, q. ,7 a. 1 : " Ex his omnibus accipi- 

 tur, quod sententia omnium philosophorum est, quod vegetabile, sensible, et 

 rationale in homine sunt una substantia. Et hoc expresse dicit Augustinus in libro 

 De spiritu et anima." (ed. Borgnet, XXXV, 90 b) . 



*° De spiritu et anima, cap. 9: " Vegetatur tamen (humanum corpus) et movetur 

 et crescit et humanam formam in utero recipit, priusquam animam rationalem 

 recipiat. Sicut etiam virgulta et herbas sine anima moveri et incrementum habere 

 videmus." (PL 40, 784-5) 



Daniels von Morley Liber de naturis inferiorum et superiorum," ed. K. 

 SudhofT, Archiv fiir die Geschichte der Naturioissenschajten und der Technik, VIII 

 (1918). See A. Birkenmajer's remarks on this edition, ibid., IX (1920), 45-51. 



