Schumpeter

The THeory of Economic Development, English edition, Internet Library (1934).

The Entrepreneur

"Chapter 2: The Fundamental Problem of Economic Development"

While in the accustomed circular flow every individual can act promptly and rationally because he is sure of his ground and is supported by the conduct, as adjusted to this circular flow, of all other individuals, who in turn expect the accustomed activity from him, he cannot simply do this when he is confronted by a new task.

While in the accustomed channels his own ability and experience suffice for the normal individual, when confronted with innovations he needs guidance. While he swims with the stream in the circular flow which is familiar to him, he swims against the stream if he wishes to change its channel. What was formerly a help becomes a hindrance. What was a familiar datum becomes an unknown. Where the boundaries of routine stop, many people can go no further, and the rest can only do, so in a highly variable manner. The assumption that conduct is prompt and rational is in all cases a fiction. But it proves to be sufficiently near to reality, if things have time to hammer logic into men. Where this has happened, and within the limits in which it has happened, one may rest content with this fiction and build theories upon it. It is then not true that habit or custom or non-economic ways of thinking cause a hopeless difference between the individuals of different, classes, times, or cultures, and that, for example, the  'economics of the stock exchange’  would be inapplicable say to the peasants of today or to the craftsmen of the Middle Ages. On the contrary the same theoretical picture    in its broadest contour lines fits the individuals of quite different cultures, whatever their degree of intelligence and of economic rationality, and we can depend upon it that the peasant sells his calf just as cunningly and egotistically as the stock exchange member his portfolio of shares. But this holds good only where precedents without number have formed conduct through decades and, in fundamentals, through hundreds and thousands of years, and have eliminated unadapted behavior. Outside of these limits our fiction loses its closeness to reality...  

We can assume that every healthy man can sing if he will. Perhaps half the individuals in an ethically homogeneous group have the capacity for it to an average degree, a quarter in progressively diminishing measure, and, let us say, a quarter in a measure above the average; and within this quarter, through a series of continually increasing singing ability and continually diminishing number of people problem, the motive power of a great number of significant phenomena... We come finally to the Carusos. Only in this quarter are we struck in general by the singing ability, and only in the supreme instances can it become the characterising mark of the person. Although practically ail men can sing, singing ability does not cease to be a distinguishable characteristic and attribute of a minority, indeed not exactly of a type, because this characteristic — unlike ours — affects the total personality relatively little.