Nyarlathotep Part 12 The Moon

...that the shrieks of cities
might less horribly disturb the pale, pitying moon
as it glimmered on green waters
gliding under bridges,
and old steeples crumbling
against a sickly sky.


In 1528 a rimester published these lines:

Yf they saye the mone is belewe, {blue}
We must believe that it is true.

The next year "green cheese" entered the picture in the lines of another writer:

They woulde make men beleue ... {believe}
that ye Moone is made of grene cheese."

Apparently, there were two schools of thought back in the early sixteenth century--one maintaining that "ye Moone" was made of "grene" cheese, and the other stoutly affirming that it was "belewe."

These ancient humorists were just punsters with a taste for metaphor; for by "green cheese," it was not the color but the freshness that was referred to-- the moon, when full and just rising, resembling both in color and shape a newly pressed cheese.

By "blue cheese" the ancient reference was to a cheese that had become blue with mold, metaphorically transferred, probably, to the comparatively rare appearance of the moon on unusually clear nights when the entire surface of the moon is visible although no more than a thin edge is illuminated.

Thus, our phrase "once in a blue moon" may actually date back to the sixteenth-century saying that "the mone is belewe." [1]

--From: A Hog on Ice and Other Curious Expressions,
Charles Earle Funk [2], Harper, New York, 1948

1 In Chrispy's neck of the woods, a "blue moon" is meant to connote a rarity. The moon, cycling about every 29.5 days, rarely exhibits a full moon twice in a single month.

2 Funk was an incredible source of etymology.