卦 are the divinatory diagrams of 《
易经》 (the I Ching / Book of Changes), built from solid (
阳爻) and broken (
阴爻) lines. The 8 trigrams (
八卦, three lines each) represent fundamental natural phenomena — heaven
乾, earth
坤, thunder
震, water
坎, mountain
艮, wind
巽, fire
离, lake
兑 — and combine into 64 hexagrams.
算卦 means 'to cast a divination'.
