136 DANIEL A. CALLUS 



cenna for the unity thesis and Avicebron for the pluralist 

 theory, Gundissalinus being the immediate channel through 

 which the same problem reached the schools. 



In thirteenth-century writings A\acebron is expressly men- 

 tioned less than Avicenna (the Schoolmen, it seems, were some- 

 what shy of referring to him by name) ; yet his influence is not 

 to be underrated, chiefly among the so-called Augustinians and 

 in the Franciscan school, particularly at Oxford. 



There were, however, other factors which helped to strengthen 

 the pluralist theory. Not least among these was the De differ- 

 entia spiritus et animae of Costa-ben-Luca,"** the Constabulinus 

 of the schools. This short treatise exerted no little influence on 

 medieval physiological and psychological thought. From it 

 Gundissalinus in his De anima borrowed Plato's and Aristotle's 

 definitions of the soul.^^ It helped to sanction the difference 

 between ' spirit ' and ' soul ' ^° and to posit an intermediary 

 uniting the soul to the body. The soul is united to the body by 

 means of a corporeal ' spirit,' which, inasmuch as it comes 

 forth from the heart, produces life, breath and beating of the 

 pulse; as proceeding from the brain, it causes sensation and 

 movement."^ Further, Costa-ben-Luca holds that the three 

 powers of the soul, the vegetative, the sensitive and the ra- 

 tional, are forms and genera of soul, and may at choice be called 

 animae.^- Thus, by introducing an ambiguous teraiinology, he 

 rendered an already involved theory even more confused. 



The Liber de causis, springing from the same Neo-Platonic 



^* Excerpta e libra Aljredi Anglici De mofu cordis. Item Costae-ben-Lucae De 

 diferentia animae et spiritus liber translatus a Johanne Hispalensi, ed. C. S. Barach 

 (Bibl. Phil. Med. Aetatis, II), Innsbruck, 1878. 



^* Cf. Gundissalinus, De anima, chap. 2 (ed. Muckle, pp. 37-41) . 



^° The difference between spiritus and anima is also clearly stated by Isaac 

 Israeli in his Liber de definitionibus, translated by Gerard of Cremona, ed. by J. T. 

 Muckle in Archives d'hist. doctr. et litt. du M.-A., XI (1937-38), 318-19. 



*^ Costa-ben-Luca, De differentia animae et spiritus, cap. 4 (ed. cit., p. 138) ; 

 cf. cap. 1, pp. 121, 124, and cap. 2, pp. 124, 130. 



" Nunc loquarum de virtutibus animae, et dicamus, quod primae virtutes 

 animae, quae sunt ei formae et genera, sunt tres: prima, scilicet vegetativa, secunda 

 sensibilis, tertia rationalis, et hae virtutes vocantur ad placltum animae." op. cit., 

 cap. 3, p. 137. 



