According to the teachings of the Buddha Shakyamuni, recorded in the Sutra on Entering the Womb, there are four classes of illness.
The first includes illnesses which are relatively inconsequential, and from these illnesses one will recover whether or not one takes medicines.
The second class of illness includes more serious, even dangerous, illnesses, but if one takes the appropriate medicines, one will recover from these as well. A modern update of this category would surely include many effective modern medical procedures, such as acupuncture, surgery, radiation therapy, chemotherapy, etc.
The third class of illness includes those for which medicines are of no use, illnesses from which one cannot recover simply through the use of medicines or other medical procedures. These illnesses, however, can be cured, and one can thereby recover one’s health, through the practice of appropriate spiritual techniques taught in the Buddha dharma.
The fourth class of illness includes those which have a karmically determined irreversibly terminal nature. When one’s body manifests such an illness, death is inevitable and no amount of medicine or medical procedure can prevent it. In fact, the use of medicines in such cases—with the exception of narcotics for pain—only serves to increase one’s suffering.
The teachings on the Medicine Buddha in the book entitled Medicine Buddha Teachings (Ithaca, New York: Snow Lion Publications, 2004) given by the extraordinary Tibetan meditation master and scholar Khenchen Thrangu Rinpoche, are intended most particularly for those who are suffering from the third class of illness, illnesses for which no successful medical treatment has been found, but which are still curable through the practice of profound spiritual techniques.
In the Buddhist tradition the most notable of these techniques are the spiritual practices associated with the Medicine Buddha. Through such practices, the innate healing powers inherent in the basic nature of all sentient beings can be uncovered and accessed. In this way sick persons can cure themselves of the illnesses that medicines and medical procedures are unable to cure.
As normal human beings we have a tendency to think that illnesses are physically based and require physical solutions. Therefore, it is reasonable to ask how it is possible that spiritual practice can help the body cure itself. This question becomes even more critical for those who have no faith in the miraculous powers of a creator god. But if one has confidence in or even an intimation of any kind of spiritual reality that transcends the limitations of a strictly material universe, then one will find oneself extremely interested in the answer to this question provided by the Buddhist tradition.
Source: Based on Khenchen Thrangu Rinpoche. Medicine Buddha Teachings. Oral translation by Lama Yeshe Gyamtso. Introduced, edited, and annotated by Lama Tashi Namgyal. Ithaca, New York: Snow Lion Publications, 2004. (pp. vii-viii)
The third class of illness includes those for which medicines are of no use, illnesses from which one cannot recover simply through the use of medicines or other medical procedures. These illnesses, however, can be cured, and one can thereby recover one’s health, through the practice of appropriate spiritual techniques taught in the Buddha dharma.