John MAynard Keynes 

• British economist 
• Governments should spend their way out of the Depression
• Borrow money to be repaid after economy recovers
• Deficit financing
• Projects should be of value to the country
• Went against Adam Smith's theories
• USA, Japan and Hitler's Germany all use this with success

Summary

John Maynard Keynes was economist who developed the theory of spending your way out of a depression. It was that the level of employment is determined, not by the price of labour, but by spending of money. His theory was quickly adopted and made successful by many nations like Japan, USA, and Germany.