"Mammon slept. And the beast reborn spread over the
earth and its numbers grew legion. And they proclaimed the times
and sacrificed crops unto the fire, with the cunning of foxes. And
they built a new world in their own image as promised by the sacred
words, and spoke of the beast with their children. Mammon awoke,
and lo! it was naught but a follower."
from The Book of Mozilla, 11:9
A virtual Easter egg is an intentional hidden message, in-joke
or feature in a work such as a computer program, web page, video
game, movie, book or crossword. The term was coined—according
to Warren Robinett—by Atari after they were pointed to the
secret message left by Robinett in the game Adventure. It draws a
parallel with the custom of the Easter egg hunt observed in many
Western nations as well as the last Russian imperial family's
tradition of giving elaborately jeweled egg-shaped creations by
Carl Fabergé which contained hidden surprises.
The reference to the Book of Mozilla above is an easter egg that
has followed Netscape/Firefox's internet browser history. There are
many examples of such great classics, including a full flight
simulator hidden in Microsoft Excel 1997.