Meanwhile, the definitive liberal response to the Great Depression was given by the English economist John Maynard Keynes (1883-1946). Keynes had been "brought up" as a classical liberal, but especially after World War I became increasingly a welfare or social liberal.[75] A prolific writer, amongst many other works, he had begun a theoretical work examining the relationship between unemployment, money and prices back in the 1920s.[76] His The General Theory of Employment, Interest and Money was published in 1936,[77] and served as a theoretical justification for the interventionist policies Keynes favoured for tackling a recession. The General Theory challenged the earlier neo-classical economic paradigm, which had held that, provided it was unfettered by government interference, the market would naturally establish full employment equilibrium.