24 o AGE, GROWTH, AND DEATH 



of. And now at three months we find another great 

 discovery is made by the baby, that it is possible to 

 bring the sensations which it receives into combina- 

 tion with the movements which it makes. It learns 

 to co-ordinate its sensory impressions and its motor 

 responses. We hardly realise what a great role this 

 adjustment, between what our muscles can do and 

 what our senses tell us, plays in our daily life. It is 

 the fundamental thing in all our daily actions, and 

 though by habit we perform it almost unconsciously, 

 it is a thing most difficult to learn. Yet the baby has 

 acquired the art, though he only gradually gets to be 

 perfect in it. Again we see, at the end of the fourth 

 month, that the baby begins to show some idea of an- 

 other great principle the idea that it can do some- 

 thing. It shows evidence of having purpose in what 

 it does. Its movements are no longer purely acci- 

 dental. At four months we find yet another equally 

 astonishing addition to the achievements of this mar- 

 vellous baby. He makes the amazing discovery that 

 the two sides of an object are not separate things, but 

 are parts of the same. When a face, for instance, 

 disappears by a person's turning around, that face, to 

 a baby of one month, probably simply vanishes, ceases 

 to exist : but the baby at four months realises that 

 the face and the back of the head belong to the same 

 object. He has acquired the idea of objects existing 

 in the world around him. That is an enormous 

 achievement, for this little baby has no instructor; he 

 is finding out these things by his own unaided efforts. 



