Ragnar Frisch was one of the founders of economics as a modern science and won the first ever Nobel Prize for economics in 1969. He is famous for coining a number of terms such as econometrics and macroeconomics which are common currency today. This set of lecture notes is a rare exhibition of Frisch's overview on econometrics. Its accessible and astute description of economic and econometric modelling versus economic reality shines a timeless warning light especially for those who are deeply lost in the thick mist of formal technique twiddling.