An Etymological Dictionary of the German Language/Sorge
Sorge, f., ‘care, anxiety, sorrow,’ from the equiv. MidHG. sorge, OHG. soraga, f., whose Franc. variant sworga makes it probable that the word was derived from an Aryan root swerk (to which OIr. serc, ‘love,’ is allied?) or Aryan swergh (comp. Lith. sergéti, ‘to guard’). Yet the forms in the other Teut. dials. have not the w; comp. Goth. saúrga, AS. sorh, E. sorrow, Du. zorg, OSax. sorga. Nothing certain can be asserted concerning the early history of the word.