As if they are off to some great meeting, flights of birds in groups silently cross the leaden Jerusalem sky, beyond the cypresses and antennae. Where are they going? It is an early winter morning, a rainless interval in a rainy season. Looking at them, the way they group, in small numbers and in large contingents, separate, merging, splitting off, but all in unison and all in the same direction, all heading, so it seems, towards the same goal. Had an avian pope given a rousing speech somewhere? Are they heading off for an avian Jerusalem?
The First Crusade is a mystery that no historian has satisfactorily explained, though many have tried, and none more comprehensively and persuasively than the late Professor Jonathan Riley-Smith. It remains entirely unreasonable that so many people, few of whom could have had any knowledge of warfare or means of support, might on such short notice choose to head off into what for the vast majority would have been entirely uncharted waters.
But that is precisely what they did. And if you think about it, human beings often behave in irrational ways. There is no reasonable explanation for the march of folly of 1914-18, or the systematic slaughter of the holocaust. Perhaps it is a futile exercise to try to make heads or tails of the First Crusade, of its spontaneity, of its scale. Sudden and vast mass movements of population can result from invasion by an aggressive enemy or an approaching or predicted natural disaster, but that was not the case in late eleventh century Europe.
Of the many and varied explanations for what motivated tens of thousands of people to go on crusade, social and economic factors might have some weight, but they cannot explain the extent of the phenomenon. Even people who live in squalor, in desolate places, who struggle for their survival in abject poverty or live under harsh regimes, rarely leave their homes. People continue to live in the shadow of rumbling volcanoes, in crime infested favelas and on shores exposed to tsunamis. If we consider the scale of the crusade, we are inevitably drawn back to the one obvious motivating factor; one that defies logic, that is unique to the human race, that can be a great source of fulfilment, but that is capable of kicking up a storm in which rationality is entirely lost in the dust.