I love examining the way Tolkien's contemplations on art and creation are represented in the Silmarillion.
In the context for his desire for publication, Tolkien expresses in his letters the view that "a solitary art is no art". I personally do not interpret this as a dismissal of the endeavour and feeling that is necessary for (sub)creative efforts that do not see the light of day. But we can certainly derive that Tolkien sees art as something that draws on the world and is to be put back into the world. In his work Melkor, who does not want his creation to draw from the existing world or from God but wants it to be solely the product of his own thought, while also having little regard of how his creations will affect the world when put out into it, is condemnable in Tolkien's narrative.
At one point in his letters Tolkien points out his inconsistent use of the word 'magic'. He uses it both in the relation to the Machine, which implies "all use of external plans or devices (apparatus) instead of development of the inherent inner powers or talents — or even the
use of these talents with the corrupted motive of dominating: bulldozing the real world, or coercing other wills."
This is juxtaposed to Elven 'magic', the object of which "is Art not Power, sub-creation not domination and tyrannous re-forming of Creation." Yet even Elven creation presents the fanger of 'Fall".
There is no parthenogenesis in art. Art is affected by thoughts, ideas, morality and aesthetics that are prexisting, but it is shaped through an osmosis of those external things with the individual creator's personal touch. And what comes out from this process is both something old and something new.
The Silmarils, which are the product of Elven sub-creation and magic) are a great example of this. Feanor captured in them part of the Light of the Two Trees. They were an osmosis of something created by Yavanna with Feanor's own ideas and craftsmanship. But Feanor did not care to help the world he lived in. He would withhold the Silmarils when their Light was needed. This too is seen as condemnable in the narrative. In a way it reflects Melkor's predicament of "the sub-creator wishing to become Lord and 'God' of his private creation", which slowly but surely leads to a desire for power. The Fall of the Elves is directly tied to Feanor and his sons' desire to not share Feanor's masterpieces with others. Their Fall is tied to "their possessiveness and (to a less degree) [to their] perversion of their art to power."
Overall art is presented as a process that is deeply social in its conception, its sub-creation AND its reception. I'd also argue that it is presented as something that is not meant to be completely controlled, not even by the sub-creator, after their endeavour is done. And this is something that Tolkien seems to have struggled with too, despite the ideas he expressed in his letters and in his work.
