Arthur Pigou (1877-1959) was an noted English economist. Pigou attributed the movements business cycle to human sentiment – the upward swings being caused by excesses of optimism and the downward swings being caused by excesses of pessimism. Pigou is well know for his work in Welfare Economics.
Adam Smith (1723-1790) was a Scottish moral philosopher and political economist. His book The Wealth of Nations is widely viewed as a foundational work in the field of economics.