It is often seen that in households where all members are exposed to the same danger, or again in schools or troops where everyone lives the same life, disease does not strike everyone indifferently.
The appearance of aged persons is too well known to make detailed description necessary. The skin of the face is dry and wrinkled and generally pale. The hairs on the head and the body are white. The back is bent, and the gait is slow and laborious, whilst the memory is weak. Such are the most familiar traits of old age.
In the ancient world and, above all, among the Greeks, human nature was held in high esteem.
Inflammation as understood in man and the higher animals is a phenomenon that almost always results from the intervention of some pathogenic microbe.
The adoration of human nature by the Greeks appeared in Greek plastic art and was the cause of its excellence.