“There was Eru, the One, who in Arda is called Ilúvatar; and he made first the Ainur, the Holy Ones, that were the offspring of his thought, and they were with him before aught else was made. And he spoke to them, propounding to them themes of music; and they sang before him, and he was glad.” 

The opening passages of The Silmarillion can be compared to the first words of creation as seen in the Christian Bible. The opening lines show Eru creating the world, setting the tone not just for the novel but for Middle-earth itself. As evidenced by the quote above, this is a world built on a foundation of lyricism and song. The world is—quite literally—sung into existence by Eru and the Valar. As such, it suggests that this will be a world where song, music, and similar types of beauty will be admired above all else. The musicality of the Elves is testament to this. Song is not just the beginning point for Tolkien’s universe, but it is the substance of the universe itself. The sharing of music, songs, and legends become one of the defining traits of the world and The Silmarillion as a self-aware text is evidence of this. Eru’s song of creation is the internal mythology of The Silmarillion. 

“‘Truly, Water is become now fairer than my heart imagined, neither had my secret thought conceived the snowflake, nor in all my music was contained the falling of the rain.’” 

This quote is attributed to Ulmo, Lord of Waters. Once the world has been created by the Valar and Eru, the Valar begin to come to terms with the nature of the world they have helped to create.