Rainbow Quiz - Identify the personality - Week 10

Here is the next weekly "Rainbow" quiz , where I would be giving 7 clues (Hence the name Rainbow) about a personality. Try to discover the person in the least number of clues . You can either leave the answer as a comment / email me . Feedback/ suggestions welcome. Googling is not preferred but then its just for fun and so go ahead if you need to.

His ideas have deeply influenced the governance in nations around the world.

clue # 1 : His stint in India was the inspiration for his first book, a brief mono graph on "Indian Currency and Finance" published before the first world war.

clue # 2 : X had a brilliant record as a stock investor even after taking a massive hit during the Stock Market Crash of 1929.

clue # 3 : After the great depression , he urged the US president FDR to do more deficit spending , a term much unheard during those days. FDR commented that "X must be a mathematician rather than a political economist".TIME magazine famously later commented that " His radical idea that governments should spend money they don't have may have saved capitalism."

clue # 4 : As the world embraced his ideas, he made it to the cover of the TIME magazine almost 20 years after his death.

clue # 5 : X was a formidable debater. Bertrand Russel commented that " Every time I argued with X, I felt I was taking my life in my hands".

clue # 6: His expression "In the very long run we are all dead" is still popularly quoted.

clue # 7 : His magnum opus, Y (name of the book) laid the foundation for the branch of economics termed "Macroeconomics" today (At least most of it).

Who is X ?