LOGIC OF RECEFTS. 6 1 



brush with his hind hands, but even so it was very difficult for 

 him to get the first turn of the screw to fit into the thread ; 

 he worked at it, however, with the most unwearying perse- 

 verance until he got the first turn of the screw to catch, and 

 he then quickly turned it round and round until it was 

 screwed up to the end. The most remarkable thing was 

 that, however often he was disappointed in the beginning, he 

 never was induced to try turning the handle the wrong way ; 

 he always screwed it from right to left. As soon as he had 

 accomplished his wish, he unscrewed it again, and then 

 screwed it on again the second time rather more easily than 

 the first, and so on many times." 



The above is extracted from the diary kept by my sister. 

 I did not myself witness the progress of this research with the 

 hearth-brush, as I did so many of the other investigations suc- 

 cessfully pursued by that wonderful animal. But I have a per- 

 fect confidence in the accuracy of my sister's observation, as 

 well as in the fidelity of her account; and, moreover, the point 

 with which I am about to be concerned has reference to what 

 followed subsequently, as to which I had abundant oppor- 

 tunities for close and repeated observations. For the point is 

 that, after having thus discovered the mechanical principle of 

 the screw in that one particular case, the monkey forthwith 

 proceeded to generalize, or to apply his newly gained know- 

 ledge to every other case where it was ac all probable that the 

 mechanical principle in question was to be met with. The 

 consequence was that the animal became a nuisance in the 

 house by incessantly unscrewing the tops of fire-irons, bell- 

 handles, &c., &c., which he was by no means careful always to 

 replace. Here, therefore, I think we have unquestionable 

 evidence of intelligent recognition of a principle, which in the 

 first instance was discovered by "the most unwearying per- 

 severance" in the way of experiment, and afterwards sought 

 for in multitudes of wh(jlly dissimilar objects.* 



• The reader is rcfcrre<l to the whole biography of this monkey {.tttimnl Intelli- 

 f^eme, pp. 4S4-498) for a numl>cr of other facts serving; to show to how h:'.;h a 

 level of intelligent grouping— or of '* logic "' — leccpts may attain without the aiJ 



