Why is E.R. Eddison's Worm Ouroboros set on Mercury?

It’s always nice to learn an author’s answer to a vexing question about their works. A new (to me) small cache of letters from the early 1930s provided some enlightenment.

In the early 1930s a young American fan sent letters to some of his favorite authors of fantasy and science fiction, asking for autographs, and sometimes making comments and asking questions. This young fan, Richard Wolford Dodson (1915-2002), became a very distinguished scientist, working on the Manhattan Project at Los Alamos in the Second World War, and later he founded and ran the Brookhaven National Laboratory's Chemistry Department.  

Like many readers of E.R. Eddison’s The Worm Ouroboros, Dodson wondered why it was set on Mercury. So in writing Eddison on 26 December 1933, after fulsome praise of the book he noted:

Only one thing about the story would I have had otherwise: its place. Mercury is so tiny a planet, so near the sun. One of its small hemispheres must be piteously [and] constantly fried by the heat. This doesn't jibe with the story, whose atmosphere is distinctly that of earth. The tale is too vast, possessed of too much grandeur to be pinned down to such a prosaic clod as Mercury. Why must Dreamland and Carce and all the other fabulous lands be definitely located?  Wouldn’t it be artistically better to have their position indefinite in both time and space? I should have preferred it that way. [Note 1, text from a draft of the letter retained by Dodson]

Eddison replied on 21 January 1934:

Perhaps you are right about Mercury. But I meant it as a pure convention. As you say, the world of the Worm is so obviously earth-like (or heaven-like?) that it should make the reader dismiss any idea of astronomical accuracy. Probably the martlet told L[essingham] it was Mercury in order to stop him asking too many questions! [Note 2]

The mentions of Mercury first appear in the opening “Induction” in conversation between Lessingham and his wife. In chapter one, after Lessingham and the little black martlet have landed “as in a dream,” the martlet tells Lessingham, “thou, first of the children of men, art come to Mercury."

Eddison continued:

Lessingham himself, & the whole Induction, are perhaps little more than machinery for letting the reader down gently into another world. But personally I have an affection for L. & for his wife (née Lady Mary Scarnside), & I am glad I made their acquaintance in this book, if only because they have, after 10 years or so, furnished me with the theme for a new book which I hope will be out before long. [ibid.]

The book to which Eddison refers took a year to come out. Mistress of Mistresses: A Vision of Zimiamvia was published by Faber & Faber of London in January 1935, and by E.P. Dutton of New York in July 1935.

 

Notes: 

1. "Richard Dodson letter to Eric Rocker Eddison 1933-12-26", Richard W. Dodson Collection of Science Fiction, Digital Initiatives, University of Idaho Library

2. "Eric Rocker Eddison letter to Richard Dodson 1934-01-21", Richard W. Dodson Collection of Science Fiction, Digital Initiatives, University of Idaho Library