Emerson famously said, "People are lonely because they don't build bridges, but build walls to enclose themselves."

Biography of Wu Jun in Song Dynasty: "You are fond of reading history, and anyone who can learn from it is also a motto."

Pessimists say: There are countless walls in this world.

Optimists say: There are countless doors in this world.

Realists say that the world is made up of countless walls and communication doors.

The door is at your hand and the wall is in your heart.