The Nei Jing is truly a cornerstone of acupuncture. It comprised of 162 articles divided into two sections, each composed of multiple books. In the first book, Su Wen, or "Fundamental Questions," the conversation clarifies points of medical theory. The second book is named Ling Shu, or "Spiritual Axis/Pivot " and is essentially an acupuncture manual. These two texts together explain the the yin-yang theory, the incorporation of the five-phase doctrine, and also provide a focus on individual symptoms as natural order rather than supernatural events. Furthermore, the channels were illustrated as carrying qi, described partly as a product of the body and partly as a product of the environment. " Virtually all medical texts that have survived since this period owe much to the Huang Di Nei Jing, in fact it is not an overstatement to say that they are based upon it." (Y. Huan & K. Rose, pg 155).
Another major contributor to the development of Chinese Medicine was Zhang Zhongjing. He was a medical scientist in the later part of the Eastern Han Dynasty. He read ancient medical classics, collected folk prescriptions and then, in combination with his own clinical experience, wrote the monumental medical work Treaties on Febrile and Other Diseases. By febrile diseases he meant epidemic cholera, malaria, pneumonia, flu and other infectious diseases. The "other diseases" mentioned in the title of his book refer to internal, surgical and gynecological ailments. In the book, he elaborated traditional Chinese medical theory and principles of treatment, laying the foundation for treatment based on differential diagnosis. Later, he came to be known as the "Sage of Medicine", because of his outstanding contribution to Chinese medicine. His book was also regarded as the "classic of medicine," and it remains a classic work of reference today for the study of traditional Chinese medicine.
Hua Tuo was also an outstanding medical scientist during the late Eastern Han Dynasty.