Why do entrepreneurs appear, not continuously, that is singly in every appropriately chosen interval, but in clusters? Exclusively because the appear… - Joseph Schumpeter

Economists have never allowed their analysis to be influenced by psychologists of their time, but have always framed for themselves such assumptions about psychical processes as they have thought it desirable to make.

Many things may be copied by the latter; the example as such also acts upon them; and many achievements directly serve other branches too [...].

The more the process of development becomes familiar and a mere matter of calculation to all concerned, and the weaker the obstacles become in the course of time, the less the “leadership” that will be needed to call forth innovations. Hence the less pronounced will become the swarm-like appearance of entrepreneurs and the milder the cyclical movement.