ORIGINS OF THE PROBLEM OF UNITY OF FORM 131 



since the higher possesses all that the lower has and something 

 more besides: the higher the soul, the greater the power, the 

 more comprehensive its virtue. The power which supervenes, 

 being stronger, becomes the principle of that which preceded 

 and remains the only principle and cause of all the powers 

 and virtues operating there. Similarly with regard to the sen- 

 sitive and rational souls, just as when the sensitive soul super- 

 venes, the vegetative is superseded, so with the appearance of 

 the rational soul all the operations both of the vegetative and 

 of the sensitive are effected by the rational. The latter vir- 

 tually includes the former, not in the sense that we can dis- 

 tinguish in the sensitive two souls or substances, and in the 

 rational three, but in the sense that one single soul, the highest, 

 has the power to produce all the operations performed by the 

 vegetative and the sensitive souls.^* 



Gundissalinus reaches the same conclusion in Chapter II, 

 when he is discussing the substantiality of the soul. The soul is 

 a substance and not an accident, since there is one soul only in 

 a living composite, whether it be a tree, an animal or a man. 

 To prove, in turn, the unity of the soul, he argues that it is the 

 soul that makes man what he is and imparts to him his specific 

 nature, for it is the self-same principle that bestows life and 

 movement, and governs and acts in man. It is not by reason 

 of two or more principles, but by virtue of the self-same prin- 



^* " Quaedam non recipiunt nisi animam vegetabilem tantum, quaedam vero 

 amplius quia animalem; quaedam vero multo amplius quia rationalem. Quemad- 

 modura si corpus unum ponatur ad solem cuius situs talis esse potest ut non 

 recipiat a sole nisi calorem tantum; si vero talis fuerit eius situs ut recipiat 

 ab eo calorem et illuminationem, tunc simul calefiet et illuminabitur, et lux 

 cadens in illud erit principium calefaciendi illud: sol enim non calefacit nisi radio. 

 Deinde si maior fuerit eius aptitudo ut etiam possit accendi, accendetur et fiet 

 flamma, quae flamma erit etiam causa calefaciendi et illuminandi simul ita ut 

 quamvis sola esset, tamen perficeretur calefactio et illuminatio, et praeter hoc 

 calefactio poterat invenire per se sola, vel calefactio et illuminatio sola per se, 

 quorum posterius non esset principium a quo emanaret prius. Cum autem omnia 

 simul concurrunt, tunc id quod fuerat posterius fit principium etiam prioris et 

 emanat ab eo id quod erat prius. Sic ergo dispositionem virium animarum facile 

 intelligere poteris, si per corpus calefieri intelligas illud tantum vegetari, et per 

 illuminari illud ab anima sensificari, per accendi vero animam rationalem sibi 

 infundi." Ibid., p. 46. 



