270 RECENT PROGRESS OF THE THEORY OF VISION. 



which are not capable of direct verbal expression. For instance 

 when we say that we ' know ' l a man, a road, a fruit, a perfume, 

 we mean that we have seen, or tasted, or smelt, these objects. 

 We keep the sensible impression fast in our memory, and we 

 shall recognise it again when it is repeated, but we cannot 

 describe the impression in words, even to ourselves. And yet 

 it is certain that this kind of knowledge (Kennen) may attain 

 the highest possible degree of precision and certainty, and is so 

 far not inferior to any knowledge (Wissen) which can be ex- 

 pressed in words; but it is not directly communicable, unless 

 the object in question can be brought actually forward, or the 

 impression it produces can be otherwise represented as by 

 drawing the portrait of a man instead of producing the man 

 himself. 



It is an important part of the former kind of knowledge to 

 be acquainted with the particular innervation of muscles, which 

 is necessary in order to produce any effect we intend by moving 

 our limbs. As children, we must learn to walk; we must 

 afterwards learn how to skate or go on stilts, how to ride, or 

 swim, or sing, or pronounce a foreign language. Moreover, 

 observation of infants shows that they have to learn a number 

 of things which afterwards they will know so well as entirely 

 to forget that there was ever a time when they were ignorant 

 of them. For example, every one of us had to learn, when an 

 infant, how to turn his eyes toward the light in order to see. 

 This kind of ' knowledge ' (Kennen) we also call ' being able ' to 

 do a thing (konnen), or ' understanding ' how to do it (verstehen), 

 as, ' I know how to ride,' ' I am able to ride,' or ' I understand 

 how to ride.' 2 



It is important to notice that this ' knowledge ' of the effort 

 of the will to be exerted must attain the highest possible degree 



1 In German this kind of knowledge is expressed by the verb kennen (cog- 

 noscere, connaitre), to be acquainted with, while wissen (scire, savoir), means 

 to be aware of. The former kind of knowledge is only applicable to objects 

 directly cognisable by the senses, whereas the latter applies to notions or con- 

 ceptions which can be formally stated as propositions. TR. 



2 The German word konnen is said to be of the same etymology as kennen, 

 and so their likeness in form would be explained by their likeness in meaning. 



