Water embracing the world.

Oceanus (Ὠκεανός) was among the oldest gods of Greek myth, the firstborn child of Uranus and Gaia and one of the twelve Titans. Unlike his brothers, however, he took no part in the Titanomachy, and so Zeus did not punish him. The Greeks believed the earth was a flat disc, and that a great river -- Oceanus -- flowed around the rim of that disc, encircling it. Oceanus was no mere sea but "the sacred river that flows along the boundary of the world." He was the source of every river, spring, and well, and the sun, moon, and stars were believed to sink into his current each day and rise again from it. Hesiod recorded that Oceanus married his sister Tethys and fathered three thousand river-gods and three thousand sea-nymphs, the Oceanids. In the Iliad, Homer called him "Oceanus, father of gods and men" (πατήρ θεῶν τε καὶ ἀνθρώπων). The word ocean entered English in the 13th century, the name of Oceanus passing whole into the language.

Sahae (四海) means, literally, "four (四) seas (海)." The ancient peoples of East Asia believed that all under heaven (天下) -- that is, the known world -- was surrounded by four seas: the eastern, western, southern, and northern. Yet sahae was not merely a geographic notion; it became a metaphor for "the whole world," "all of humankind." The most famous expression appears in the Yan Yuan chapter of the Analects: "Sima Niu lamented, saying, 'All men have brothers; I alone have none.' Zixia said, '... If a gentleman is reverent and without fault, courteous and observant of propriety toward others, then all within the four seas are his brothers'" (四海之內, 皆兄弟也). Thus sahae was a metaphor for a universal love of humanity reaching beyond blood. It also expressed the reach of the emperor's authority -- "to rule the four seas" (統四海) meant to be emperor of all under heaven. In later ages the expression sahae was used across every domain: politics, diplomacy, religion, and poetry alike.