The Mastery of Medicine from the Yellow Emperorís Classic
Huang Di said, "Indeed. Do not forget that the myriad things of the universe have an intimate relationship with one another. They may present as varied as yin and yang, internal and external, male and female, upper and lower, but they are all interconnected, interdependent, and intertranscendent. Let us take medicine, for example. As a medical practitioner, one should master the cosmologies of heaven and earth, understand the human mind and spirit, and grasp all sciences of nature. In this way one will have a holistic, integrated perspective, and will grasp the Tao. One can then teach the wisdom and allow it to survive everlastingly. But putting the knowledge in books becomes a precious medium of transmission."
From the Yellow Emperor's Classic page 287---