The mainland sees "one country". Others in Hong Kong prefer "two systems". Between these two antithetical positions, many of us on both sides have thought we could fudge this nebulous, contradictory but supremely useful formula, at least until 2047.
That is becoming a political fantasy. You must now belong to one camp or the other. If you are for democracy, you must be against the central government; and vice versa. You are no longer allowed to make judgments on case-by-case merit. For or against. One side or the other. Choose.
It appears the centre is quickly losing its hold.
Tit for tat. For every action on one side, there is an equal or even fiercer reaction from the other. That is now the political discourse in Hong Kong.
Disgruntled young Hong Kong men waved the colonial flag to spite mainland officials. That provoked the rude remark of Lu Ping, a former Hong Kong and Macau affairs chief, that advocates of independence were "sheer morons". His former deputy, Chen Zuoer, warned pro-independence forces were "spreading like a virus".
Former justice secretary Elsie Leung Oi-sie blasted local judges and the legal profession for misunderstanding Hong Kong-mainland relations and the top court for making mistakes. This led Mr Justice Kemal Bokhary to warn of "a storm of unprecedented ferocity" over rule of law and the Bar Association to denounce her.
Now Zhang Xiaoming, a top mainland official in charge of Hong Kong affairs, has predictably provoked a furious backlash after alleging external powers are helping the city's opposition parties and that "necessary measures" such as implementing a national security law are needed to counter them.
If we had a competent government, it might be able to mitigate the mutual disregard and antagonism. But it is proving to be hapless or worse.
Tragedy is said to be the clash between two rights. "One country" and "two systems" are both valid. But combining them required the greatest of pragmatism and goodwill on both sides. That's precisely what we are running short of.
Yeats was right: "The falcon cannot hear the falconer/Things fall apart; the centre cannot hold."