Happy birthday today to Richard Strauss (1864-1949). Perhaps his most iconic piece of music (due in huge part to filmmaker Stanley Kubrick opening his film "2001: A Space Odyssey" with it) is the "Sunrise" opening of his tone poem Also sprach Zarathustra from 1896. But there's so much more music after that, a total of nine sections lasting over 30 minutes. It's better to say that Strauss did not base his music on the book of the same name by Friedrich Nietzsche but was inspired by it. Strauss wrote in a letter,  

“I never intended to write philosophical music, nor did I seek to portray Nietzsche’s great work in music. Rather I wanted to convey, through music, some idea of the development of the human race, from its origins, through the different stages of its religious and scientific development, to Nietzsche’s concept of the Superman." 

Strauss ultimately left only chapter headings from the book as titles to the movements and, thus, clues to the programmatic content. But one observation to take away is that in the music nature, or the universe, is represented by the key of C major while humanity, mankind, is represented in B major and these two are in conflict - or they perhaps more accurately, contrast - throughout the entire work, leaving the two keys to alternate at the very end and leave the famous "unanswered question" of whether humanity or nature predominates.

Listen to conductor Marin Alsop compare Nietzsche's writing to Strauss's music in this NPR interview (with music):
https://www.npr.org/2012/01/14/145168801/alsop-sprach-zarathustra-the-conductor-decodes-strauss-iconic-tone-poem