The law is not easy to spread, and the Tao is not cheap.
When the teacher is not on the way, the doctor doesn't knock.
Law and Tao have many meanings. Method: technique, method, method (gate diameter), Tao, technique, etc. Tao: truth, Tao and doorway. Generally speaking, Dharma and Taoism originally refer to the ways, methods or theories of practicing in Buddhism and Taoism. Here refers to all kinds of skills, theories, principles, methods and so on. (As the teacher said, a teacher is a teacher, so it is also possible to preach and teach. Tao here also refers to all theories, principles, methods and so on. Although "Tao" is not a patent of Taoism, "Tao" did evolve from Taoism. )
Don't pass it easily, just don't pass it casually. Don't sell it at a low price, which is similar to the meaning of not spreading it easily, and it also means not to teach it easily.
Teachers and doctors, this is easy to understand, were originally teachers who taught books and doctors who saved lives. But the teacher here means learning, not a verb.
Not on the road, that is to say, you should have the sincerity to study, not on the road to study. Doctors don't close the door, and people who practice medicine don't take the initiative to come to save people, which is easy to be regarded as a liar. In addition, it also implies that practicing medicine is not cheap and doctors need to be given enough respect. Similarly, the previous "teachers don't pass by" also implies this meaning, and you should also respect teachers when you study.