A Mission to Jerusalem, a High Risk, High Reward Idea

The pope called for an expedition to recapture jer usalem. This was a really crazy, off the wall, a unlikely idea. And yet, it seems pope urban decided that this was a high risk, but high reward bargain and he took it. Why jerusalem? Well, obviously jerusalem has greater religious significance than than constantinople does. But it had a particular kind of religious significance that fit a very tightly into the beliefs and practices of mediaeval western christianity in a way that made it much more powerful of amot vator than  constantinople or the eastern empire.