Indeed, not only do contemporary events radiate instantaneously – now we can be said to be feeling the impact of all past events in a new way. For the past is doubling back on us. We are caught in what might be called a "time skip."

An event that affected only a handful of people at the time of its occurrence in the past can have large-scale consequences today. The Peloponnesian War, for example, was little more than a skirmish by modern standards. While Athens, Sparta and several nearby citystates battled, the population of the rest of the globe remained largely unaware of and undisturbed by the war. The Zapotec Indians living in Mexico at the time were wholly untouched by it. The ancient Japanese felt none of its impact.

Yet the Peloponnesian War deeply altered the future course of Greek history. By changing the movement of men, the geographical distribution of genes, values, and ideas, it affected later events in Rome, and, through Rome, all Europe. Today's Europeans are to some small degree different people because that conflict occurred.

In turn, in the tightly wired world of today, these Europeans influence Mexicans and Japanese alike. Whatever trace of impact the Peloponnesian War left on the genetic structure, the ideas, and the values of today's Europeans is now exported by them to all parts of the world. Thus today's Mexicans and Japanese feel the distant, twice-removed impact of that war even though their ancestors, alive during its occurrence, did not. In this way, the events of the past, skipping as it were over generations and centuries, rise up to haunt and change us today.

When we think not merely of the Peloponnesian War but of the building of the Great Wall of China, the Black Plague, the battle of the Bantu against the Hamites – indeed, of all the events of the past – the cumulative implications of the time-skip principle take on weight.