[听力原文]
There are three branches of medicine. One is called "doctor medicine" or "scientific medicine." Doctors try to observe illnesses, look for logical patterns, and then find out how the human body works. From there they figure out what treatments may work. This kind of medicine is believed to sate from the 4th century BC. Although nowadays it’s successful, in the ancient world this approach probably didn’t cure many patients.
A second kind of medicine is called "natural cures," or "folk medicine," in which less educated people try to cure sicknesses with various herbs. These folk healers also use observation and logic, but they are not so aware of it. They try things until they find something that seems to work, and then they keep doing that. Folk medicine flourished long before the development of scientific medicine and was more successful in ancient times.
The third kind is called "health spas," or "faith healing." Sometimes this may be as simple as touching the holy man and being immediately healed. Other times, a magician may give you a magic charm to cure you. Some religious groups set up special healing places. There people take a rest, get plenty of sleep, eat healthy food, drink water instead of wine, exercise in various ways. They also talk to the priests and pray to Gods. If you are feeling depressed or you have been working too hard, going to these places may be just the right thing to do.

What is the speaker’s primary purpose in this passage（）