"Questions of convergence under an infinite time horizon will depend so much on epsilontic refinements in the system of assumptions — and on the infinite constancy of these refinements — that we are humanly speaking absolutely certain of getting infinite time horizon results which have no relevance to concrete reality. And in particular we are absolutely certain of getting irrelevant results if such epsilontic exercises are made under the assumption of a constant technology. 'In the long run we are all dead.' These words by Keynes ought to be engraved in marble and put on the desk of all epsilontologists, in growth theory under an infinite horizon."

“In this feverish world of ours, where one wants the economic analyses to produce easily understandable results quickly and at the least possible cost, some of us have fallen into the habit of assuming for simplicity that the hundreds sometimes thousands of variables that enter into the analyses are linked together by very simple relationships. Frequently we even go so far as to assume linear relationships. Only in this way have we been able to feed our problems into the electronic computers and get mechanical answers quickly and at low cost.”

“Usually it is easier to obtain estimates for budget proportions and Engel elasticities than for elasticities with respect to price. By making certain want independence assumptions, the elasticities with respect to price can be deduced from the knowledge of budget proportions and Engel elasticities. In this connection the concept of the flexibility of the marginal utility of money is essential. A system of formulae decribing these relations is given.”

“We may predict that the science of which we try to be the humble and devoted servants will in the future life of the nations be an important factor in eliminating maladjustments between fundamental economic sectors and assure a smooth and progressive utilization of resources... One wants men with a knowledge of the characteristic features of the economic and social structure of their country and with a fundamental theoretical knowledge along modern lines.”

“length of the cycles and the tendency towards dampening are determined by the intrinsic structure of the swinging system, while the intensity of the fluctuations is determined primarily by the exterior impulse. An important consequence of this is that a more or less regular fluctuation may be be produced by a cause which operates irregularly.”

“The propagation problem is the problem of explaining by the structural properties of the swinging system what the character of the swings would be in case the system was started in some initial situation”

“the unification of economic theory, statistics and mathematics.”