Therefore too， if and when thatdefinition shifts ground —— if and when \"our place in the world\" be-gins to change， it can be the equivalent of an earthquake leaving inits wake the rubble of centuries and， for the survivors， either thepossibility of rebuilding some new combination of places， or migrat-ing to safer ground. Naturally， such earthquakes are not everydayoccurrences and， normally， their impact is only local. They tend tooccur only at moment when， rather like the tectonic forces of theearths plated themselves， two self- definitions come into directconflict and one is forced to give way （space） to the other.