What is the idea of original sin? How does it affect developing countries when they face a devaluation or depreciation of their currency? How does it affect developed countries when they face a devaluation or depreciation of their currency?

Consider two countries, Greece and Germany, that have joined a monetary union and suppose Greece is prone to sudden changes in the demand for their exports. What does this look like in the GG-LL graph and how does it affect their membership in the union?