Final answer:
Early economic thought rooted in classical economics, emphasized land as the primary limiting factor to growth and held a 'hands off' policy approach. The classical view was upended by the Great Depression, ushering in Keynesian economics which supports active governmental fiscal and monetary policies.
Step-by-step explanation:
The origins of early economic thought date back to classical economists like Adam Smith, David Ricardo, Thomas Malthus, and John Stuart Mill. These foundational economists based their theories in natural philosophy and mostly agreed that economic growth was constrained by the availability of land, which was the primary resource for production outputs at the time. They could not predict the subsequent technological advancements and the exploitation of fossil fuels which dramatically shifted economic development and theory. The classical economic theory assumed a self-regulating economy that would naturally adjust back to full employment without any active fiscal or monetary policy interventions. However, the Great Depression catalyzed a shift in economic thinking, paving the way for Keynesian economics, which advocates for government intervention to manage and stimulate the economy during periods of low aggregate demand.