Economics is the science of choice born out of the existence of scarcity. Because resources are limited, everyone cannot have everything. Thus we have a certain amount of supply and of demand for that supply, and somehow a choice will have to be made on how that supply is allocated.
Economics views a choice is an incurred cost. For example, in Robert Frost’s poem, the road less traveled is taken at the cost of the road frequently traveled. Choices assume liability for a cost. Eating a sandwich is at the cost of feeding the sandwich to your kittens and feeding the sandwich to your kittens is at the cost of the satisfaction the sandwich would bring you.
That is why this kitten understands economics in nine works: “There ain’t no such thing as a free lunch.” TANSTAAFL (pronounced “Tan-staffle”). He knows that every lunch fed to him is at the cost of using those resources of time, food, and animals in other ways. With this knowledge, he can correctly view everything from daily choices to political decisions. When someone makes a choice, he asks himself “But what is the cost?”
To read more about this topic check out The TANSTAAFL Principle