Memory lane: I memorised this poem for French class in summer school, 1980. The following year I rediscovered the poem when studying Renaissance French poetry during senior year of high school, and also heard the haunting musical version for the first time from the local college chorale.
I dont know why the last one says anonymous. The poem is Ode à Cassandre by Pierre de Ronsard (1524-1585), and the musical version, usually known by the opening line Allons voir si la rose, was composed by Guillaume Costeley (1530-1606).
(Note: the singers arent incompetent speakers of French; theyre trying to capture the Renaissance pronunciation.)