The major strength of Wolf's book - his concentration on interaction, intermingling and mutual modification - is at the same time its major weakness,… - Eric Hobsbawm

Increasingly, therefore, the formal international structure came to diverge from the real one. International politics became global politics, in which at least two non-European powers were to intervene effectively, though this was not evident until the twentieth century. Furthermore, it became a sort of oligopoly of capitalist-industrial powers, jointly exercising a monopoly over the world, but competing among themselves; though this did not become evident until the era of ‘imperialism’ after the end of our period.

To draw a parallelism between the arts and the sciences is always dangerous, for the relationships between either and the society in which they flourish is quite different. Yet the sciences too in their way reflected the dual revolution, partly because it made specific new demands on them, partly because it opened new possibilities for them and faced them with new problems, partly because its very existence suggested new patterns of thought.

The progress of science is not a simple linear advance, each stage marking the solution of posing of problems previously implicit or explicit in it, and in turn posing new problems.