The melody comes from the last movement of Beethoven's Ninth Symphony, finished in 1824 and first performed in Vienna on 7 May that year. Beethoven set it to Friedrich Schiller's poem An die Freude (To Joy): the cellos and basses introduce it quietly on their own, the orchestra takes it up, and then the soloists and choir sing it - voices in a symphony, which no major composer had done before.
The plainness is deliberate. Beethoven's sketchbooks show him reworking the tune again and again to make it simpler and easier to sing. It has been the anthem of the European Union since 1985 (without the words), and Leonard Bernstein conducted the symphony in Berlin at Christmas 1989 to celebrate the fall of the Wall, with "Freude" (joy) sung as "Freiheit" (freedom).
This transcription: Beethoven, Symphony No. 9 in D minor, Op. 125 (1824), finale: the "Freude" theme, transposed to C major; left hand by GOONS Studio.
Transcribed by GOONS Studio from the original work, which is in the public domain.
For kids: Ode to Joy by colors, on a rainbow piano that lights the next key and waits.