Adam Smith, better known as the "Father of Economics", in his work "The Wealth of Nations" presented his considerations and theories that were consistent with English classical political economy. With his metaphor "Invisible Hands", he described the unconscious endeavors of an individual that can inadvertently have a positive effect on the economic situation in the country. Joseph Schumpeter, although a student of the neoclassical school of economics, managed to devise his own theory that emphasized the importance of innovation for revenue generation. As for the monetary theory of John Keynes, he sought to understand the reason for keeping the interest or non-interest assets of an economic unit if the income of the same is less than other forms of assets. Milton Friedman, on the other hand, advocated economic liberalism. He emphasized his disagreement with the Keynesians in every situation because he considered their interpretation of the role of money within economic activity to be wrong. Robert Lucas also disagreed with Keynes' teaching. He pointed out that fiscal policy could worsen the already existing bad situation in the country. His contribution to macroeconomic theory has inspired many other Nobel laureates, such as F. Kydland and E. Prescott. Monetary theory gained its "opportunity" immediately with the appearance of the COVID-19 pandemic. The key elements of MMT could be very helpful if used appropriately.