“Hymne à l'amour” (hymn to love) is Piaf's declaration of absolute love. The blue sky could collapse and the earth could fall apart — she wouldn't care, as long as he loves her. She'd go to the end of the world, dye her hair, give up her country, if he asked her to. And if death takes him, they'll be together forever in the blue sky.
Piaf wrote the words for the boxer Marcel Cerdan, the love of her life, who died in a plane crash in 1949; she sang it in 1950 and it became one of her most famous songs.
It's slow and grand, sung with total clarity. The structure “si tu me le demandais” (if you asked me) is a beautiful example of the French conditional.