He said: water can carry a boat, but it can also overturn it. It shows that he is in awe of the power of the people.
He said: with copper as a mirror, you can be well dressed; Taking history as a mirror, we can know the rise and fall; Take people as a mirror, you can know the gains and losses. It shows that he is open-minded, teachable and courageous to reflect on himself.
He said: officials have people, but not many people. It shows that he clearly realizes that those who win the hearts of the people win the world and pay attention to the integrity of the official.
He said: the wind knows the grass, and the board swings to know the loyal minister. Knowing people and making good use of them is brilliant.
All these qualities show that Emperor Taizong was a great emperor. It laid the foundation for the prosperous Tang Dynasty.