The purpose and real value of systems engineering is... to keep going around the loop; find inadequacies and make improvements. - Robert E. Machol

We assert that it is possible to describe analytically any human function which can be reasonably defined in objective terms and we specifically include in such functions "thinking" insofar as that term is definable. If by "thinking" one means being able to do arithmetic, or play a good game of chess, or learn from experience, or make optimal decisions in exceedingly complex situations, then we assert that thinking can be described analytically. And there are two important corollaries: if It can be described analytically, it can be simulated; and if it can be simulated, it can be performed mechanically.

Everyone knows what engineering is. All that's left is to define systems, and I'm not fool enough to do that.

Sometimes, where a complex problem can be illuminated by many tools, one can be forgiven for applying the one he knows best.