 
                            
                        
                        
                        “A system is more than the sum of its parts; it is an indivisible whole.”
                                        
                                        It loses its essential properties when it is taken apart. The elements of a system may themselves be systems, and every system may be part of a larger system. 
Ackoff (1973) "Science in the Systems Age: beyond IE, OR and MS." in: Operations Research Vol 21, pp. 664. 
1970s
                                    
