Song by Ravel (written around 1898), to a text from Chansons écossaises (1852) by Charles-Marie-René Leconte de Lisle (1818-1894), leading poet of the Parnassian movement. The song was first performed and published in 1975.
In the last verse, Ravel makes his only musical reference to Gregorian chant by quoting the Dies irae in the piano accompaniment. (Orenstein  p.146).
The text of the song can be found on the Lied and Song Texts Page.