Economics is not a human invention. It is a set of naturally occurring innate human dynamic activities.
Material Aspect: In everything we do, we use some material 'thing designed for that particular function or adapted for some [particular] purpose' (SOED*) to better succeed at that 'function' or 'purpose' and, therefore, at that human dynamic. The handling of the material aspects of our human dynamics is economics.
CHAPTER ONE: The BASIC PURPOSE of economics and the FIVE PRIMARY AXIOMS that begin the subject.
The BASIC PURPOSE drive for material needs and wants compel into utility all of the different human mental and physical capacities necessary for material success. They are stated as 'FIVE PRIMARY AXIOMS': The FIVE PRIMARY AXIOMS contain within them the single clockwork of 'TWELVE ELEMENTAL ACTIVITIES' evolved to achieve all human material needs and wants.
CHAPTER TWO: The TWELVE ELEMENTAL ACTIVITIES / the 'PRIMARY OPERATING DYNAMICS' of Economics
PRODUCE, CONSUME, EDUCATE, RESOURCES, TRADE, ETHICS, GAIN, ORGANIZE, EMPLOY, CURRENCY, SPECIALIZE, SYMBIOSIS
The very doing of this single clockwork of interlocking dynamic activities is what the subject of economics is all about. Their very activity generates into existence...
CHAPTER THREE: The DERIVATIVE [or SUBORDINATING] OPERATING DYNAMICS' of Economics
If you've studied academic economic 'theory', these are the concepts you are already familiar with - however, not necessarily from a productive perspective. Economics is an active dynamic activity. Read GAIN: The Dynamics of Successful Economic Outcome.