There is no grass on the crowded road, and there is no hair on the head of wisdom. What does this mean?

There is no grass on the crowded road: in Lu Xun's words, there is no road in the world. If more people walk, it will become a road.

Wisdom has no hair on its head: it is explained by a common saying: it is extremely clever.

Well, from the reality, it is difficult for plants to grow on crowded roads, because the soil is too hard, because it is constantly trampled. Bald people are partly caused by insufficient hair nutrition supply, and some of these people are caused by excessive brain use. These people are prone to baldness because of more mental work.