geometric · from c. 800 BCE
The Eight Trigrams
Eight stacks of three broken or unbroken lines — a complete three-bit notation, arranged in a ring and hung over doorways.
What the sources claim for it
A complete set of states. Hung at a threshold, the claim is that nothing can arrive that is not already accounted for.
History
Where does the Eight Trigrams come from?
Each trigram is three lines, each either solid or broken, giving exactly eight combinations; stacked in pairs they give the sixty-four hexagrams of the Yijing. Two standard arrangements exist, attributed to Fuxi and to King Wen, and the difference between them is a live question in the commentary tradition.
In domestic use the eight trigrams are set around a mirror and hung above a door as a protective device. That is the same job as a nazar or a hamsa, done with what is essentially a diagram of a number system — which makes it one of the very few wards in this corpus that is also a piece of formal notation.
Afterwards
What did it turn into?
Read by Leibniz in 1703 as binary arithmetic, which it structurally is; central to modern feng shui practice; and on the flag of South Korea in a reduced four-trigram form.
Which texts describe it?
Oldest first, with what each one does with the mark. A mark described in a Bronze Age incantation and a mark first drawn in a seventeenth-century manuscript are different kinds of claim, whatever the shape has in common.
Shanhaijing (Classic of Mountains and Seas)
Anonymous · 4th c. BCE - 2nd c. CE · Classical Chinese
The classical Chinese cosmological corpus the trigram system belongs with.
Read Shanhaijing (Classic of Mountains and Seas) in full ↗Cover: Public domain · National Library of China · Wikimedia file page
Nearby
Related marks
The Fu Talisman
A strip of yellow paper carrying characters that are not quite characters — a written order to the spirit bureaucracy, issued under seal.
The Taijitu
Two interlocking halves, each carrying a dot of the other — a Song-dynasty diagram of a much older idea, not an ancient emblem.
The Triple Spiral
Three joined spirals cut into a kerbstone at Newgrange five thousand years ago — older than the pyramids, and completely unexplained.
The Pentagram
A five-pointed star drawn in one unbroken line — an accounting mark, a Pythagorean password, a Christian emblem of the five wounds, and only recently a sign of evil.
The Ouroboros
A serpent swallowing its own tail, first drawn around the sun god in an Egyptian tomb and still in use three thousand years later as a diagram of a closed system.
The Dharmachakra
An eight-spoked wheel for an eightfold path — the emblem Buddhism used for its founder for four centuries before it would depict him at all.