John Maynard Keynes 
The General Theory of Employment, Interest and Money. Illustrated 

The General Theory of Employment, Interest and Money caused a profound shift in economic thought, giving macroeconomics a central place in economic theory and contributing much of its terminology – the ‘Keynesian Revolution’.
Keynes denied that an economy would automatically adapt to provide full employment even in equilibrium, and believed that the volatile and ungovernable psychology of markets would lead to periodic booms and crises. The General Theory is a sustained attack on the classical economics orthodoxy of its time. 

About the author

David Ricardo (18 April 1772 – 11 September 1823) was a British political economist, one of the most influential of the classical economists along with Thomas Malthus, Adam Smith and James Mill. He was also a politician, and a member of the Parliament of Great Britain and Ireland.