Gilles Deleuze, interpreting a passage in Arnold Toynbee, says that Toynbee "shows that nomads in the strict, geographical sense are neither migrants nor travelers, but on the contrary, those who do not move, those who cling on to the steppe, who are immobile with big strides, following a line of flight on the spot, the greatest inventors of new weapons. But history has never begun to understand nomads, who have neither past nor future." I like the literary (not a logical) paradox there. Yes, if we think of an American "snow bird," travelling every November from New York to Florida, traveling every April back to New York, then we can think of him changing his habitat and remaining constant in his habit. Year after year this comes to look less like travel than like immobility with big steps. Toynbee was all about challenge and response. The Big Picture in his writings is that a civilization faces some crisis and either responds creatively or fails. If its ...