I am the cause
 
Sag, allerliebstes Kind,
  Say,     all-beloved            child,
     bin ich’s, um den Du weinst?
         am    I      it (the one)  about whom you are weeping?
Ach ja, Du siehst mich an,
  Ah yes,        you   look at    me,
     ich bin’s wohl, den Du meinst.
          I      am  it (the one) well, whom you mean.