Q.In which book, and in what year, did Keynes present his theory of employment?

Keynes wrote this book directly in response to the mass unemployment of the Great Depression.

John Maynard Keynes presented his theory of employment, output and money in The General Theory of Employment, Interest and Money, published in 1936. Keynes wrote the book as a direct response to the Great Depression of the 1930s, when mass, prolonged unemployment across the industrialised world could not easily be explained by classical economics, which held (via Say's Law) that a lasting general glut of unsold goods and idle workers should not occur. The book is regarded as the founding text of macroeconomics as a distinct branch of economics, and introduced concepts …