A marvellous song!
Well in case the translation says nothing to you, i'm gonna write the story.
In Greece we had a civil war after WWII. After the famous Yalta Conference, there was a major conflict between communists and anti-communists.
After that period we had a non-stable republic which eventually ended by a 7 years military goverment (1967-1974).
For all these years the communist party was an outlaw organization and so communists were considered as outlaws.
After the stabilization of democracy and the legalization of the communist party in 1975 there were many generations of communists that had already spent their entire life as fugitives in their own country.
The song is a dedicated to them, as a statement that newer generations recognized their fight for their beliefs (that's why it refers the word "demonstration.").
Note that Manos Loizos who wrote (and firstly recorded) this song was a self taught musician.
"Gilgamesh, where are you hurrying to?
You will never find that life for which you are looking.
When the gods created man they allotted to him death,
but life they retained in their own keeping"