…history proceeds in such a way that the final result always arises from conflicts between many individual wills, and every one of them is in turn made into what it is by a host of particular conditions of life. Thus there are innumerable intersecting forces, an infinite series of parallelograms of forces which give rise to one resultant – the historical event. This may in its turn again be regarded as the product of a power which operates as a whole unconsciously and without volition. For what each individual wills is obstructed by everyone else, and what emerges is something that no one intended.
Engels to Joseph Bloch in Königsberg; London, September 21[-22], 1890, Marx Engels, Selected Correspondence, Progress Publishers, Moscow, 1982, 395