Academic historians of the last hundred years or so get all stiff and tweedy when you suggest that people will go to all ends for the sake of their religion. They'll assure you that religion is just a cover for other, more "rational" motivations. They would prefer to explain the world in terms of economic self-interest, of class warfare, or of dynastic imperatives. But has not the early twenty-first century made it catastrophically clear how many people (and not just the desperate, either) are ready to leap over the brink in the name of their religion? The same was certainly true of "the age of discovery." While greed should certainly be given her due, there is no reason to think that da Gama was not perfectly sincere when he said that he came in search of Christians and spices.