Future, Yeasts, Witchcraft, Subterranean Journey

Question

OK, Stackers, here's another nugget from my imperfect memory of forgotten future and sci-fi paperbacks.

Read, in paperback, somewhere between 1963 and 1966.

Humanity seems to be in a subterranean location with many levels, perhaps forced to live there, perhaps due to yeast plagues or wars. Yeasts seem to be a recurring motif in the novel.

Written from the viewpoint of a single, relatively young male, who may be a member or agent of a secret society. He is compelled to take a journey through some of the levels. He had survived a yeast plague because his mother was a prolific home baker. A level he traverses has an inland beach and swimmable sea, with an artificial sun and horizon, he swims out to the fuzzy edge and finds a metal wall. On the beach (sorry) he converses with a man and meets a dog he sees (with psi power-like x-ray vision) has an internal growth, he recognizes it as a second brain. The dog becomes his guide for a while, they communicate empathically.

He meets a woman, they greet each other with the modern Wicca-like phrase of "Blessed be", another motif. There is mention of the Athame (a ceremonial knife). He has visions of acting as a Cretan bull-leaper, this vision is an analog for other psi powers.

The novel ends optimistically for the hero and humanity, memories are restored, he is more fully received into the society.

NOT "A Boy and His Dog" (Ellison), though I appreciate the similarities.

I commend my soul, and these snippets to the greater group memory: anybody, anything?

Answer 1

''Sign of the Labrys'' by Margaret St. Clair, published 1963

Her protagonist, Sam Sewell lives in a post-apocalyptic world, a world where horrific yeast based diseases killed off most people.

....

Despoina in the meanwhile is not quite what the FBY agent told Sam. Sam soon learns she is a Witch, though not the sort of witch Sam first thinks of, the stereotypical old hag who rides a broomstick. What she is, is what we now would call Wiccan, something that the title of the novel hints of already. A Labrys is a double headed ritual axe, as used in Minoan religious rites in ancient Greece and later adopted by neopagans. Sam Sewell, as you may guess has to be initiated into Witchhood and Despoina is the person who has to lead him to the Craft. Witches have of course superhuman powers and they need Sam to help better the world. Their opponents being the FBY, who are busy trying to establish a dictatorship.