The Eight Diagrams from Chinese Mythology - a given sequence of open and closed lines, here used as a good luck charm.
 
YIN and YANG at the Centre of the Pah-kwa - the Eight Diagrams.
 
 
The diagram sugnifying the union of contraries/opposites.
 

chinese symbolism from
Researches into Chinese Superstitions
M.Kennelley SJ, T'Usewei Printing Press Shanghai 1922.

The Ogdoad, in Paracelsian theory, the eight matrices of the Universe.

The number of the Beatitudes, see Matthew v 3-11.

Cloud cover is measured in eight parts called `oktas'; complete cloud cover is eight oktas.