In the cosmologies of many cultures and civilisations, an egg gives rise to the universe upon its hatching. In others it gives rise to a primordial being who, in turn, creates the universe. The egg is sometimes laid on the primordial waters of the Earth. Typically, the upper half of the egg, or its outer shell, becomes the heavens and the lower half, or the inner yolk, becomes the Earth. The motif stems from the basic elements of an egg, including its ability to offer nourishment and give rise to new life.

Leda and the Swan, Leonardo da Vinci’s famous lost painting from 1508, depicts a nude standing Leda cuddling the swan, with the two sets of infant twins. On the ground, there are large broken eggshells. Leda laid two eggs, from which her children hatched. Helen was one of them. Swan Song is a metaphor for a final gesture, effort, or performance given just before death. The phrase refers to an ancient belief that swans sing a beautiful song just before their death, having been silent for most of their lives.