The General Theory of Employment, Interest and Money is a book by English economist John Maynard Keynes published in February 1936. It caused a profound shift in economic thought, giving macroeconomics a central place in economic theory and contributing much of its terminology – the "Keynesian Revolution". It had equally powerful consequences in economic policy, being interpreted as providing theoretical support for government spending in general, and for budgetary deficits, monetary intervention and counter-cyclical policies in particular. It is pervaded with an air of mistrust for the rationality of free-market decision making. 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. It introduced the concepts of the consumption function, the principle of effective demand and liquidity preference, and gave new prominence to the multiplier and the marginal efficiency of capital. Keynes's aims in the General Theory The central argument of The General Theory is that the level of employment is determined not by the price of labour, as in classical economics, but by the level of aggregate demand. If the total demand for goods at full employment is less than the total output, then the economy has to contract until equality is achieved. Keynes thus denied that full employment was the natural result of competitive markets in equilibrium. In this he challenged the conventional ('classical') economic wisdom of his day. In a letter to his friend George Bernard Shaw on New Year's Day, 1935, he wrote: I believe myself to be writing a book on economic theory which will largely revolutionize — not I suppose, at once but in the course of the next ten years — the way the world thinks about its economic problems. I can't expect you, or anyone else, to believe this at the present stage. But for myself I don't merely hope what I say,— in my own mind, I'm quite sure. The first chapter of the General theory (only half a page long) has a similarly radical tone: I have called this book the General Theory of Employment, Interest and Money, placing the emphasis on the prefix general. The object of such a title is to contrast the character of my arguments and conclusions with those