五行 Wuxing

六經論五行者始見於尚書洪範曰一五行一曰水二曰火三曰木四曰金五曰土大禹謨曰水火金木土穀惟修其源起於河圖洛書之數蓋圖書之一六水也二七火也三八木也四九金也五十土也在圖則左旋而相生在書則右轉而相克也然土於圖書為五十中宫之數無定位無專體者也惟呂氏春秋則以土直季夏之月以順相生之序白虎通又以土直辰戌丑未之四季而分旺於四時文王後天圖象坤艮二土獨居夏秋冬春之交則以火必得土而後能成金水必得土而後能生木也今按行也者言其行於地者也質行於地而氣通於天數之有五焉故曰五行也地者土也以其對天言之則曰地以其質言之固土也土之為四行君也固也君則不專其司不居其部是故以火之克金而秋乃承夏令也則謂既有四方必有中央而中央固土也可以嗣火之老而生金也以春秋冬夏之遞嬗四行轉多而土轉少也則謂季月必辰戌丑未而辰戌丑未固土也減十二日以與本令餘十八日為土王用事則各七十二日也坤艮二土居四氣之交為土之真體則後天圖象明之乾巽二方據魁罡之戶示土之神用則素問運氣詳之土之君乎四行也審矣然此猶皆為有象可示者也若其無象可示者則寅申己亥子午卯酉實無一之離乎土焉何也非土則水火金木不能以行其能以行者皆土也

The earliest mention of the Wuxing in the Six Classics appears in the Shangshu (Book of Documents), specifically in the chapter Hong Fan _ctext, which states: One, the Wuxing: 1 is ㊌_WATER, 2 is ㊋_FIRE, 3 is ㊍_WOOD, 4 is ㊎_METAL, and 5 is ㊏_EARTH.

The Wuxing refer to their movement on the ground. Substances move on the ground, while their energies connect with the heavens, giving rise to the Wuxing.