“‘One country’ is like the roots of a tree. For a tree to grow tall and luxuriant, its roots must run deep and strong.” That metaphor came from Chinese President Xi Jinping in a keynote speech at the inauguration ceremony of Hong Kong’s fifth term government on July 1, 2017, the last time he set foot in the city that Beijing took back from the British in 1997. During the address before a 2,000-strong audience, Xi underscored the importance of abiding by the Chinese constitution and the Basic Law, the city’s mini-constitution, and urged Hong Kong authorities to seize economic...