Duration

The thirty-second hexagram, Heng ("Duration"), places Zhen (Thunder) above Xun (Wind). Thunder and wind, which always accompany one another, give the image of an enduring union that lasts through constant change. It follows Influence in the King Wen order, pairing the courtship of the young with the constancy of the settled couple.

Heng holds a further position in the xiantian, or Earlier Heaven, arrangement, the binary ordering devised by Shao Yong in the eleventh century and traditionally ascribed to Fu Xi: 36th of 64, apart from its thirty-second place in the King Wen sequence above. This was the Fu Xi ordering that the Jesuit Joachim Bouvet sent from Beijing in 1701 to Gottfried Wilhelm Leibniz, who recognized its broken and unbroken lines as his own binary 0 and 1.

Read from the bottom, the six lines of Duration run yin, yang, yang, yang, yin, yin. A later interpretive layer absent from the original Zhou Yi, the nuclear hexagram (hu gua), treats lines two through four as a lower trigram and lines three through five as an upper one; here they combine as Dui over Qian, forming hexagram 43, Breakthrough (Guai), a hidden figure first associated with the Han-dynasty scholar Jing Fang, whose Yijing commentary of the first century BCE is credited with the earliest appearance of nuclear trigrams. Duration's King Wen partner is hexagram 31, Influence (Xian); most of the sixty-four pair this way, related by turning the whole figure upside down, while the eight hexagrams built from a single doubled trigram pair instead by inverting every line. Mawangdui (1973) orders hexagrams by trigram, not King Wen; names here follow Wilhelm and Baynes, 1950, not Legge, 1882.

The Judgment, in paraphrase, promises success and freedom from blame, rewards perseverance and favors having somewhere to go, for what endures does so not by standing still but by renewing itself along a steady course. The Image speaks of the superior person who stands firm and does not change his direction. The core theme is duration and constancy, the lasting that is achieved through faithful movement rather than rigidity. Moving lines transform into their opposites, generating a second hexagram that shades the reading.

The Judgment and Image paraphrased above draw on two of the Ten Wings, commentarial texts appended to the Yijing and traditionally credited to Confucius, though the attribution was already doubted within the Chinese tradition by the eleventh century and modern scholarship instead dates their composition to roughly the fourth to second century BCE, well after the Zhou Yi core itself. Wang Bi's third-century commentary read passages like this one from Heng philosophically, playing down the trigram image-correlations earlier commentators relied on, while Zhu Xi's twelfth-century Zhouyi Benyi pushed back the other way, insisting the book remain readable as the divination manual it began as.