If we endeavour to understand the thought processes and nature of Mahavira, Gandhi, Marx and Keynes, we would be able to comprehend the systems given by them. Mahavira was not an economist in its limited sense. He was an ascetic who had renounced the world. As such, all economic principles emerge from the concept of renunciation.
Gandhi also was devoted to spiritual attainment and took the medium of politics for his objectives. He did not apparently propound an economic theory or advocated an economic system.
Marx and Keynes both were basically economists. To understand economics, it would be necessary to understand both of them. But merely by understanding economics, we cannot make the society good. Merely by increasing wealth, we cannot keep the society healthy and balanced.
Without understanding Mahavira and Gandhi, if Marx and Keynes are accepted, the social system will not remain good. A comparative study of all these four is imperative from the point of view of understanding economics. This comparative study can open up new vistas of thinking for us.