National interest means different things to different people. So it's interesting that President Xi Jinping cited it in his maiden speech as head of state to urge Hong Kong and Macau to rally behind the country.
No doubt he has intended a heavy dose of patriotism and love in his formulation. He wants to say the two special administrative regions need to consider the overall interests of the nation "to safeguard and foster [their own] long-term prosperity and stability".
State leaders have been emphasising the importance of patriotism as a criterion to pick leaders to run Hong Kong during the National People's Congress in Beijing, which ended on Sunday. But perhaps it would be better for both Hong Kong and the mainland to evolve a more realistic and business-like working relationship rather than insisting on love and blood ties.
So let's consider the more usual meaning of the phrase "national interest", something close to the heart of every political realist. It is that in politics, there are no friends, only common interests.
What Xi says makes even more sense in this context. Beijing is ready to consider anything that is in Hong Kong's interest, so long as Beijing's legitimate interests are also recognised and met. New Premier Li Keqiang said something similar afterwards, urging Hong Kong to make good and full use of the central government's economic and social initiatives to benefit the city.
Beijing has every interest to see Hong Kong prosper. But it also has legitimate or non-negotiable core interests in the city and its future development, especially in terms of democracy. One interest is surely our clear recognition that the Chinese Communist Party is the central government, which is also the only legitimate government of "one China". From this, it follows Hong Kong cannot be used as a base to challenge the legitimacy, unity and sovereignty of the Chinese state; nor can it have a leader Beijing does not trust.
Therefore, the screening of chief executive candidates is a given, though Hong Kong may still have a big say on how this can be done in a future "one person one vote" electoral franchise.
This is not what usually passes for full democracy, but it is not a bad deal, given how Beijing defines the nation's core interests.