THE SEASON WHY. 227 



'' If thou sayest, Behold, we knew it not ; doth not he that pondereth the heart 



consider it ? and he that keepeth thy soul, doth not he know it ? and shall noi 



he render to every man according to his works ?" PROVEEBS xxiv. 



950. Why are the motions of the heart, <$fc. } made 

 independent of the will ? 



Because, as the necessity for the heart's motion is fixed and 

 unalterable, the constant motion of the heart could be best secured 

 by giving it a fixed nervous influence, by which it might be 

 unfailingly prompted to fulfil its functions. 



If the movements of man's heart were subject to his will, he 

 would be constantly required to regard the operations of that 

 organ ; and so large an amount of mental care and physical 

 exertion would have to be employed in that direction, that man's 

 sole work would be to keep himself alive. Hence we see the 

 goodness of the Creator in giving life to man, and in keeping the 

 vital impulses under his divine care. 



CHAPTER XLVII. 



951. What are nerves ? 



The nerves are branches of the brain and the spinal cord ; they 

 are distributed in great numbers to all the active and sensitive parts 

 of the body. 



952. What is the spinal cord ? 



The spinal cord is a long and large cord of nervous matter, 

 which extends from the brain through a continuous tube formed by 

 corresponding hollows in the bones of the back. It serves as a 

 nervous trunk for the distribution of nerves, just as the aorta dis- 

 tributes branches of blood-vessels. 



953. Why is the spinal cord placed in the grooves formed 

 ly the back-bone ? 



Being a very vital part of the system, and from the delicacy of 

 its structure liable to injuries, it is set in the back-bone for 

 protection ; and so great is its security that it is only by force of 

 an unusual kind that it can be injured. 



