406 PSYCHOLOGY. 



philosophers, who also believed iu the distinct atomic na< 

 tureof 'ideas,' to preclude the presence to it of more than 

 one objective fact, manifested in one idea, at a time. Even 

 Dugald Stuart opines that every minimum visibUe of a pic- 

 tured figure 



"constitutes just as distinct an object of attention to the mind as if it 

 were separated by an interval of empty space from the rest. ... It 

 is impossible for the mind to attend to more than one of these points at 

 once ; and as the perception of the figure implies a knowledge of the 

 relative situation of the different points with respect to each other, we 

 must conclude that the perception of figure by the eye is the result of 

 a number of different acts of attention. These acts of attention, how- 

 ever, are performed with such rapidity, that the effect, with respect to 

 us, is the same as if the perception were instantaneous. " * 



Such glaringly artificial views can only come from fan- 

 tastic metaphysics or from the ambiguity of the word ' idea,* 

 which, standing sometimes for mental state and sometimes 

 for thing known, leads men to ascribe to the thing, not 

 only the unity which belongs to the mental state, but even 

 the simplicity which is thought to reside in the Soul. 



When the things are apprehended by the senses, the 

 number of them that can be attended to at once is small, 

 "Plu7'ibus intentus, minor est ad singula serisus." 



" By Charles Bonnet the Mind is allowed to have a distinct notion of 

 six objects at once ; by Abraham Tucker the number is limited to four ; 

 while Destutt Tracy again amplifies it to six. The opinion of the first 

 and last of these philosophers" [continues Sir Wm. Hamilton] "seems 

 to me correct. You can easily make the experiments for yourselves, 

 but you must beware of grouping the objects into classes. If you 

 throw a handful of marbles on the floor, you wall find it difficult to 

 view at once more than six, or seven at most, without confusion ; but 

 if you group them into twos, or threes, or fives, you can comprehend as 

 many groups as you can units ; because the mind considers these 

 groups only as units— it views them as wholes, and throws their parts 

 out of consideration." f 



Professor Jevons, repeating this observation, by count- 

 ing instantaneously beans thrown into a box, found that 

 the number 6 was guessed correctly 120 times out of 147, 5 

 correctly 102 times out of 107, and 4 and 3 always right. ^ 



* Elements, part i. chap, ii, Jin. 



f Lectures on Metaphysics, lecture xiv. 



t Nature, vol. in. p. 281 (1871). 



