Jacobi's song is prefaced with "Nach einem alten Liede" (after an old song). According to an article in the same journal that printed Jacobi's song (1782), Carl Wilhelm Pörner wrote (1783) that this "old song" is the Gartenlied (Garden Song) by Carl August Svabe (born c. 1711), written about 1750. He was secretary to a functionary at the court of Dresden. In this song, which became popular while Svabe was absent due to the Seven-Year's War, the author (poet) asks at the beginning of each verse:
Where are the violets
Where are the tulips
Where is the rose
Where are the girls
Where are the friends
Where is the poet

...and they're all gone, of course.

Svabe possibly based his song on an older song, either German or Italian (but I've afraid I don't have time to go into this now!).

Don