According to semiotics, which may be defined as the doctrine of the essential 
nature and fundamental varieties of signs, objects, and interpretants, pain is 
considered to be a sign (significant) with very different meanings 
(significance) either as a naturalistic symptom (of disease) or as a symbol used 
in a metaphorical context. When following this methodological perspective it is 
possible to interpret medical as well as poetic writings on equal terms. In 
Graeco-Roman medical texts pain was mostly understood as a result and an 
indicator of disease, but nonetheless as a symptom which seemed to be actively 
produced by the affected body. Especially in the Corpus Hippocraticum dating 
from the 5th and 4th century B. C. this materialistic and at the same time 
psychosomatic attitude can be noticed. Aristotle (4th century B. C.), Celsus 
(1st century A. D.), and the famous experimental physiologist Galen (2nd century 
A. D.) agreed that pain was a sign of evil which should be fought without 
exception. It was Galen who added the disturbance of function (functio laesa) as 
the fifth cardinal sign of inflammation to the four well-known cardinal signs of 
Celsus (rubor, calor, tumor, dolor). He also coined the term [see text] to 
characterize an attack of migraine. In algotherapy, Galen used a complex 
pharmacological system which was based upon the four cardinal qualities of 
humoral pathology. On the other hand, pain was designed as a multi-dimensional 
symbol by the famous Graeco-Roman epic poets. In Homer's Odyssey (8th century B. 
C.), pain appears transformed into the shape of a scar which is visible and 
palpable on the hero's leg like an identification tag, whereas in Virgil's 
Aeneids (1st century B. C.) pain symbolizes weakness and defencelessness which 
can only be alleviated by the goddess Venus.