Passage
The history of literature really began was the earliest of the arts. Man danced for joy round his primitive camp fire after the defeat and slaughter of his enemy. He yelled and shouted as he danced and gradually the yells and shouts became coherent and caught the measure of the coherent and caught the measure of the dance and thus the first war song was sung. As the idea of God developed prayers were framed. The songs and prayers became traditional and were repeated from one generation to another, each generation adding something of its own.
As man slowly grew more civilized, he was compelled to invent some method of writing by three urgent necessities. There were certain things that it was dangerous to forget and which, therefore, had to be recorded. It was often necessary to communicate with persons who were some distance away and it was necessary to protect one’s property by making tools and so on, in some distinctive manner. So man taught himself to write and having learned to write purely for utilitarian reasons he used this new method for preserving his war songs and his prayers. Of course, among these ancient peoples, there were only a very few individuals who learned to write, and only a few could read what was written.
The word 'measure' in the context of the passage means
Before man invented writing
The war song evolved out of
Man invented writing because he wanted
The first war-song
As for the war songs and prayers each generation
