 Complete the following phrase:  The theory of the Open Door Policy originated with British commercial practice, as reflected in treaties concluded with the Qing dynasty China after the First Opium War 183942. The Open Door concept was first seen at the Berlin Conference of 1885, which declared that no power could levy preferential duties in the Congo. As a concept and policy, the Open Door Policy was a principle that was never formally adopted via treaty or international law. It was invoked or alluded to but never enforced as such. The policy collapsed in 1931 when the Japanese 