If they say that man sang his swan song, then imply that he did something for the last time. If you initially do not know the meaning of this phraseologist, then you can not guess what exactly he means: it would seem, where is the swan, singing and the last thing that man did?
In order to understand the origin of the phrase "sing the Swan song", it is necessary to return to two and a half thousand years ago, namely, in ancient Greece. It was there that there was a belief that silent in the usual life of the swans before death publish a moan, similar to a song. The mention of the Swan, singing the last song before death, can be found in the work of the ancient Greek poet-basinist of Ezop, who lived in the 6th century BC. Or in the creation of Agamemnon Eschil. The poets of the Renaissance drew inspiration from the work of ancient poet and writers, so gradually the expression "swan song" appeared in the works of classics. For example, it can be found in Leonardo da Vinci records and Shakespeare.
And, as it turned out, to some extent it is true. In Zoology, swans are divided into 7 species, the most famous of which in Europe Swan-Shipun, which does not give any other sounds except hissing in the threat. But once a year, Europe visits another type of swan - the Swan-Clikun, giving sounds similar to the hum of pipes. When the Swan-Clikun dies, and the remnants of the air go out of his lungs, the special structure of the trachea sometimes contributes to the appearance of a kind of "pipe" sound, which, of course, is not at all like singing.
Two data types of swans were widely known in ancient Greece, where, by the way, the swan was considered a bird of harmony and beauty, consecrated by Apollo herself. Perhaps hearing the last exhalation of swan-clikun, the ancient writers slightly embarrassed him and turned it into a song. Over time, the peculiarity of the Swan-Clikun began to attribute absolutely all types of swans. And repeatedly mentioning the swan song in artworks secured this phraseology in many languages of the world.