"A system must be designed and tested as a complete entity. The word 'system' has come, through actual practice, to include: the prime mission equipment; its supporting command, control, training, checkout, test, and maintenance equipment; the facilities required to operate and maintain the system; the selection and training of personnel specialists; the operational and maintenance procedures; instrumentation and data reduction for test and evaluation; special aviation and acceptance programs and logistics support programs for spare and depot maintenance. All parts of a system must have a common unified purpose: to contribute to the production of a single set of optimum outputs from given inputs with respect to time, cost, and performance measures of effectiveness. The absolute necessity for coherence requires an organization of creative technology which lead to the successful design of the complex military system. This organized creative technology is called Systems Engineering."
January 1, 1970
https://en.wikiquote.org/wiki/Systems_engineering