We eat corns and bread, a body of flesh, and naturally we can have illness of any kind. But, if we have good body resistance, illness should not fall upon us and, of course, we must be very careful to take care of our body in any circumstance.
When we were born, unless we have defects in our organs which make us unable to survive, we shall be perfect to live our life with healthy body, same as a new car from factory. But, by the time gone by we grow up and get old and slowly we shall pass our life away under the cycle of nature.
However, if we take care of our organs well, we can live up to eighty or ninety without particular difficulty. It is because our body has a power itself to remedy our organs which sometime may not feel well. Our eyes and ears can serve us well up to a very old age provided a precaution is taken all the time.
Unless we have accident and suffer wound in our body, we need doctor to have operation or any other ways to cure. But, to our usual small illness, such as cold, or fever, we do not need doctor to help us. We just lie on bed for a few days and drink more water. Surely such small illness will be gone easily.