The broad philosophical theme behind this dark symphony is what Nielsen called the indestructability of the life force. He wrote, " This symphony is meant to express the appearance of the most elementary forces among humans, animals and even plants. In case, all the world were to be devastated by fire, flood and volcanoes, all things being destroyed; then, nature would still begin to breed new life again. Soon, the plants would begin to multiply, the breeding and screaming of birds would be seen and heard, the aspiration of humans would be felt. These forces, which are 'inextinguishable' , are what I have tried to present".
It is a musical drama in which the key of E Flat Major representing life wins an ultimate victory over an unstable D Minor tonality representing chaos and destruction. In the finale, we come across two timpanists who steam in from both sides of the orchestra thundering furiously. Their cannon fire is in strict canon.
Notable recordings are those by Michael Schonwandt conducting the Danish National Radio Symphony, Leonard Bernstein conducting the New York Philharmonic and Sir Simon Rattle conducting the Birmingham Symphony.