Swan

Greek myth gives the swan to Apollo, whose chariot it draws, and makes it the disguise of Zeus in his approach to Leda, a story with an enormous painting tradition behind it. The belief that a swan sings once, beautifully, at the point of death is classical: Plato has the dying Socrates invoke it in the Phaedo, arguing that the swan sings not from grief but from joy at going to the god it serves. It is also false, the whooper swan is vocal throughout its life, and the swan song is a poetic fiction that has nonetheless given English a lasting phrase. Irish tradition gives the Children of Lir, transformed into swans for nine hundred years, a tale of endurance and eventual release.

In England the mute swan carries a genuine legal history apart from its myths: by ancient prerogative the Crown holds rights over all unmarked mute swans in open water, a right now shared with the Vintners' and Dyers' livery companies, and every July an annual census called Swan Upping counts and marks the cygnets on a stretch of the Thames, a ceremony documented since at least the twelfth century and still carried out today by the King's Swan Marker in traditional scarlet uniform. The mute swan of Greek and English tradition also anchored a famous argument about certainty: for two thousand years European writers used all swans are white as a stock example of a claim proven beyond doubt, John Stuart Mill cited it as such in his 1843 System of Logic, until the Dutch explorer Willem de Vlamingh found black swans in Western Australia in 1697, a discovery that took over a century to fully unseat the proverb.

Indian tradition gives the swan, or more strictly the hamsa, often a goose rather than the mute swan of Europe, a place of high honour as the mount of Brahma the creator and of Saraswati, goddess of learning and the arts. The hamsa is credited with the ability to separate milk from water when the two are mixed, and this became a standard image for the discriminating wisdom that separates the real from the unreal, the eternal from the transient; the accomplished ascetic is called a paramahamsa, the supreme swan. The bird's whiteness, its grace on the water and its migratory freedom all feed a symbolism of purity and of the soul detached from the world it moves through.

The bird most likely meant by the Sanskrit hamsa, the bar-headed goose, is itself one of the most extraordinary fliers among birds: it migrates twice yearly directly over the Himalayas, flying at altitudes exceeding seven thousand metres where oxygen is a third of sea-level pressure, a physiological feat documented by modern tracking studies that gives an unexpected literal grounding to the hamsa's old reputation as a bird that moves between the earthly and the transcendent. Which real bird the Sanskrit hamsa names is itself debated among scholars: alongside the bar-headed goose already discussed, some argue for the greylag goose or for a partly composite, idealised bird rather than any single species, an ambiguity that has not stopped the word from giving its name to revered teachers, Ramakrishna Paramahamsa among the best known, styled the supreme swan regardless of which bird the term first pictured.