A POSTAL SYSTEM 231 



constitution and also that of the human machine are 

 altogether different from the machines designed by man. 

 Our bodies are made up of billions of microscopic living 

 units, each unit having an independent activity, and yet 

 an activity which has to be co-ordinated with the work 

 done by neighbouring units. The operations carried on 

 by one brigade of units has to be co-ordinated with the 

 activities carried on by brigades in distant parts of the 

 body. To find a parallel to such a condition we have to 

 think in terms of an army and of its elaborate organisation. 

 The human body is built like a machine, but has been 

 given the organisation of an army. How marvellous that 

 organisation is we shall proceed to show in the chapters 

 which follow. 



