Wassily Leontief

"Computers and robots replace humans in the exercise of mental functions in the same way as mechanical power replaced them in the performance of physical tasks. As time goes on, more and more complex mental functions will be performed by machines. Any worker who now performs his task by following specific instructions can, in principle, be replaced by a machine. This means that the role of humans as the most important factor of production is bound to diminish—in the same way that the role of horses in agricultural production was first diminished and then eliminated by the introduction of tractors."

"Among the many factors that have promoted economic change, I believe that technology or, rather, change in technology is the most prominent. I realize that it is dangerous to look for 'ultimate causes' in a world where everything seems to depend on everything else. But I believe that for the most part the economy, and ultimately the society, must adapt to the conditions that technology creates. If it cannot adjust to the challenges of changing technology, it fails."

"The statistical study presented in the following pages may be best defined as an attempt to construct, on the basis of available statistical materials, a of the United States for 1919 and 1929. One hundred and fifty years ago, when Quesnay first published his famous scheme, his contemporaries and disciples acclaimed it as the greatest discovery since Newton’s laws. The idea of general interdepence among the various part of the economic system has become by now the very foundation of economic analysis. Yet, when it comes to the practical application of this theoretical tool, modern economists must rely exactly as Quesnay did upon fictitious numerical examples."

"The general, and at the same time dynamic, type of analysis still remains an unwritten chapter of economic theory, the claims of innumerable “model-builders” notwithstanding... The … theoretical approach, based on the combination of the complexities of a general interdependent system with the simplifying assumptions of static analysis, constitutes the background of this investigation."

"This work may be best described as an attempt to construct a of the United States."

"The total number of multiplications involved in the practical solution of our problem exceeds 450,000. This task alone would mean a two-year job, at 120 multiplications per hour. Fortunately, the recent invention of the Simultaneous Calculator by Professor Wilbur of the Massachusetts Institute of Technology has made it possible to perform all the necessary computations in a small fraction of the time they otherwise would have required. This apparatus solves nearly automatically a system of nine simultaneous linear equations."

"How will the cessation of war purchases of planes, guns, tanks, and ships … affect the national level of employment? How many new jobs will be created by the consumers’demand for an additional one million of passenger cars, how many of these jobs can be expected to be located in the automobile industry itself, and how many in other industries such as Steel and the Chemicals, the Coal and the Petroleum industries? How much additional freight traffic and revenue can the American railroads expect to derive from every billion dollars worth spent on post-war housing construction?"

"Economics today rides the crest of intellectual respectability and popular acclaim. The serious attention with which our pronouncements are received by the general public, hard-bitten politicians, and even skeptical businessmen is second only to that which was given to physicists and space experts a few years ago when the round trip to the moon seemed to be our only truly national goal."

"Much of current academic teaching and research has been criticized for its lack of relevance, that is, of immediate practical impact... The trouble is caused, however, not by an inadequate selection of targets, but rather by our inability to hit squarely any one of them... The weak and all too slowly growing empirical foundations clearly cannot support the proliferating superstructure of pure, or should I say, speculative economic theory."

"By the time it comes to interpretation of the substantive conclusions, the assumptions on which the model has been based are easily forgotten. But it is precisely the empirical validity of these assumptions on which the usefulness of the entire exercise depends... A natural Darwinian feedback operating through selection of academic personnel contributes greatly to the perpetuation of this state of affairs."