When former president Chiang Kai-shek (蔣介石) roped the Taiwanese into his fight against the Chinese Communist Party (CCP) after taking over Taiwan, his planners explained the CCP’s basic doctrine this way: “What is mine is mine, and what is yours is also mine. Some things are to be taken as common property and I will therefore take yours.”
China and its sympathizers would say that the wording of this outline was simply an attempt to stigmatize and demonize China, but I would say it is a fairly accurate way to describe the idea of “one China.”