14 Studies in Animal Behavior 



came to be more clearly defined by the theological 

 writers of the latter part of the Middle Ages. Of 

 these St. Thomas Aquinas stands preeminent as an 

 authority on the animal mind as upon most things 

 else. Aquinas makes a sharp distinction between the 

 sensitive soul (anima sensitiva) and the intellectual 

 soul (anima intellectualis), ascribing the former to 

 brutes, and the latter only to man. Animal and man 

 are therefore separated by a broad and impassable 

 barrier. Animals have sensations, sensory memory, 

 but they have no reason (Summa Theologica, 

 LXVI and LXXXIIB), no real freedom (/. c. 

 CXIII), no responsibility. "No activity of the sen- 

 sitive part can have place without a body. But in the 

 souls of dumb animals we find no activity higher 

 than the sensitive part. That animals neither under- 

 stand nor reason is apparent from this, that all ani- 

 mals of the same species behave alike, as being 

 moved by nature, and not acting on any principle of 

 art; for every swallow makes its nest alike. There- 

 fore there is no activity in the soul in dumb animals 

 that can possibly go on without a body." (/. c. 

 LXVI.) 



"Sense," he says, "is found in all animals, but ani- 

 mals other than man have no intellect; which is 

 proved by this, that they do not work, like intellec- 

 tual agents, in diverse and opposite ways, but just 

 as nature moves them to fixed and uniform specific 

 activities." "Sense is cognizant only of singulars, 

 but intellect is cognizant of universals. Sensory 



