Is Arda earth?

[Bêthberry]

I thought that our world and the one of Arda were seperate?

It is perhaps not inappropriate to mention here Tolkien's lecture "On Fairy-Stories." For him, the act of writing fantasy or "sub-creation", to be truly successful, needs to draw upon a sense of touchstone with our own l ives.

Probably every writer making a secondary world, a fantasy, every sub-creator, wishes in some measure to be a real maker, or hopes that he is drawing on reality: hopes that the peculiar quality of this secondary world (if not all the details) are derived from Reality, or are flowing into it. If he inded achieves a quality that can fairly be describe by the dictionary definition: inner consistency of reality', it is difficult to conceive how this can be, if the workd does not in some way partake of reality. The peculiar quality of the 'joy' in successful Fantasy can thus be explained as a suddent glimpse of the underlying reality or truth.

According to Tolkien's biographer, Humphrey Carpenter, preparing this lecture gave Tolkien a renewed sense of purpose in writing LOTR. The lecture suggests that Tolkien's very purpose was to create a Middle earth which felt like it was 'real,' was part of our own world in earlier times.