Reading between the lines was a technique Western analysts used to find out what the Soviet Union was really up to during the Cold War when there was a dearth of reliable information.
The analysts paid attention to the tiniest and most obscure of indications - such as the positions of Communist Party officials at parades in Moscow's Red Square and the arrangement of stories on the party newspaper's pages - to understand what was going on in Soviet politics.
Although it has been more than 20 years since the Cold War ended, reading between the lines can still help us shed light on what senior mainland officials truly think, as it may be too simplistic to take their public comments at face value.
In a closed-door meeting with Hong Kong delegates to the Chinese People's Political Consultative Conference in Beijing on March 6, Yu Zhengsheng shared his views on the parallel-goods trade in infant formula and on mainland women giving birth in Hong Kong.
Yu, who was elected CPPCC chairman last week, said these issues were not very serious problems and that he believed the Hong Kong government would handle them properly.
Yu, who served as Shanghai party secretary until last year, spoke of his experience handling tensions in that city created by people who came from other parts of the country to give birth in that city.
After the session, some Hong Kong delegates praised the state leader for his empathy for Hongkongers' grievances over similar issues the city faces.
On the surface, Yu was expressing his support for the city government's policies in handling the mainland-Hong Kong tensions, including its curb on mainlanders taking large amounts of infant formula across the border.
If we read between the lines of the state leader's comments, we will find subtle messages have been carefully embedded in his diplomatic words.
Recounting the problems he faced in Shanghai as party secretary, Yu said that people from other parts of the mainland flocked to that city to give birth because Shanghai's medical service standards were higher and more affordable.
"How did the Shanghai municipal government handle the problem? It increased the number of beds for obstetric services [among other measures]," Yu said.
"After all, we have to serve people from other parts of our country," he said, adding that the Shanghai authorities developed an international health care service park to cope with the increase in patients.
To escalate such issues into a "one country, two systems" conflict would be to over-politicise them, he stressed.
As a state leader, Yu is obliged to publicly support the Hong Kong government's policies.
But his remarks about his experience in Shanghai are a subtle reminder to Chief Executive Leung Chun-ying's administration not to over-react in handling such sensitive cross-border issues.
He is suggesting these problems can be resolved by expanding the city's community facilities.
Even so, Yu should also bear in mind the difficulties facing the local government in building community facilities, especially in the face of opposition from numerous pressure groups, political parties and residents.