比翼双飞 (bǐ yì shuāng fēi) — Wing Beside Wing · Flying as a Pair · Setting Out Together

The bird has one eye and one wing. That is how the Jin scholar Guo Pu describes it in his note to the Erya, the early word-list, which says of it only 不比不飞: it flies only beside another. The Erya lists one paired thing for each quarter of the world, a fish in the east that does not go unless paired, the bird in the south, a beast in the west that runs with a partner, people in the north who take turns to eat and keep watch, and calls them the strange airs of the four directions. 比 is side by side. In the Chuci piece Divination, Qu Yuan asks the diviner whether he should fly 比翼 with the yellow swan or fight the chickens and ducks for food, and the Tang commentators of the Wenxuan explain 比翼 as 比肩, shoulder to shoulder.

The phrase says the same thing twice. 比翼 puts the wings side by side and 双飞 has two in flight, and the doubling is the point: one bird is not enough to make the sentence. Lu Ji, who died in 303, already joins all four characters in a single line, at the close of a poem about music heard from below a high tower. Zuo Fen, writing the court elegy for Empress Yang in 274, split the two halves across a couplet, saying of the emperor and the empress that they had flown 比翼 in a plain unpainted house and 双飞 into the purple pavilions of the palace.

At first the image was not only for couples. Taiwan's Ministry of Education dictionary still records 比翼鸟 as a figure for close friends as well as for a loving husband and wife, and for the friends' sense it quotes Cao Zhi's farewell to two companions. The lovers' sense is the one that held. In Bai Juyi's Song of Everlasting Regret of 806 the bird is the oath of an emperor and his consort; in the twelfth century the painter Yang Wujiu has a couple recall their old vow as 比翼连枝, paired wings and joined branches; and the dictionary's gloss of 比翼双飞 today is a man and woman in loving accord, joining hands to make a future together.

In the Classic of Mountains and Seas the bird is not a love token at all; it is bad news. A bird like a wild duck, with one wing and one eye, flies only when the two find each other, and when it is seen the world floods; Guo Pu's note names it the paired-wing bird. The Han historian Sima Qian records the opposite reading: Guan Zhong told Duke Huan of Qi that when the old kings made the feng and shan sacrifices, the eastern sea had sent the paired-eye fish and the western sea the paired-wing bird, and that with no such signs now the duke should not try it; the duke dropped the plan. The Book of Song's list of auspicious signs says the bird appears when a ruler's virtue reaches far. The poets who later wrote it into vows took over a bird that had already been a flood omen and a court omen.

Today it is said of and to couples. Taiwan's Ministry of Education dictionary lists 鸾凤和鸣 and 夫唱妇随 among its near-synonyms, and its example sentence under 双飞 wishes it on a husband and wife together with 白头偕老. The neighbours show what this one adds. In 夫唱妇随 the husband leads and the wife follows; in 鸾凤和鸣 the male and female phoenix call in tune. 比翼双飞 has no leader and no song. The two are level, they are moving, and neither one can make the trip without the other.