One of the euphemisms in "From Emperor to Citizen" is Puppet. It refers to Pu Yi who was called Emperor, but was actually controlled by the Japanese. Another euphemism is Forbidden City, because it wasn't forbidden for those who worked and lived there.
Someone is listening to our conversation this is the answer.
Well here the author says that inner voice of us reveals our feelings, regrets in other words what we live in our life is reflected inside of us. So he gives the example of water .Like our life, it runs quickly and our life also one day will be cut off which means it 'll come to an end. So this sheet of water is one of the pages of our life which is one part of in our long life journey.