There have been only a few very rare periods in human history, and a few very sparse regions, in which spontaneous progress has occurred. There must have been spontaneous progress in Egypt and Babylonia when they developed writing and agriculture; there was spontaneous progress in Greece for about 200 years; and there has been spontaneous progress in Western Europe since the Renaissance. But I do not think there has been anything in the general social conditions at these periods and places to distinguish them from various other periods and places in which no progress has occurred. I cannot escape from the conclusion that the great ages of progress have depended upon a small number of individuals of transcendent ability. Various social and political conditions were of course necessary for their effectiveness, but not sufficient, for the conditions have often existed without the individuals, and in such cases progress has not occurred. If Kepler, Galileo, and Newton had died in infancy, the world in which we live would be vastly less different than it is from the world of the sixteenth century. This carries with it the moral that we cannot regard progress as assured: if the supply of eminent individuals should happen to fail, we should no doubt lapse into a condition of Byzantine immobility.
Russell, Bertrand. “Western Civilization.” In Praise of Idleness. London and New York: Routledge, 2006