"Du, du liegst mir im Herzen" ("You, you are in my heart") is a German folk song, believed to have originated in northern Germany around 1820. Bavarian flautist Theobaid Boehm, inventor of the fingering system for the modern flute, composed a theme and variations for flute and piano on this tune.

 
Lyrics in English:
You, you are in my heart.
you, you are in my mind.
You, you cause me much pain,
You don't know how good I am for you.
Yes, yes, yes, yes you don't know how good I am for you.

So, as I love you
so, so love me too.
The most tender desires
I alone feel only for you.
Yes, yes, yes, yes, I alone feel only for you.

But, but may I trust you
you, you with a light heart?
You, you know you can rely on me
You do know how good for you I am!
Yes, yes, yes, yes you do know how good for you I am!

And, and if in the distance,
it seems to me like your picture,
then, then I wish so much
that we were united in love.
Yes, yes, yes, yes, that we were united in love