28 INTRODUCTION TO SCIENCE 



ascending water and salts, the descending sugar 

 and proteids. The zoologist can in the same way 

 see through the snail on the thorn, seeing as in a 

 glass model everything in its place, the nerve- 

 centres, the muscles, the stomach, the beating 

 heart, the coursing blood, and the filtering kid- 

 ney. So the human body becomes translucent to 

 the skilled anatomist, and the globe to a skilled 

 geographer. 



Similarly, on a higher plane than merely opti- 

 cal clearness, those of the scientific mood are in 

 great part trying to make the world translucent. 

 They are seeking to construct an intellectual 

 cinematograph of the long processions of causes 

 that pass unceasingly before us. A perfectly clear 

 working thought-model is what science seeks to 

 construct. 



There is so much to know that ignorance in 

 itself is no particular reproach; but the point 

 is to be clear when we know and when we do not, 

 and it is one of the characteristics of the scientific 

 mood that it will have yes or no to this question. 



"Do you see it or do you not?" was the con- 

 tinual question of a biological teacher gifted 

 with great educational ability, and "If you see 

 it, what is it like?" 



A student who worked under Agassiz relates 

 how she was almost brought to despair by the 

 severe way in which that great master, after giv- 



