An Etymological Dictionary of the German Language/Annotated/Sorge
Sorge, feminine, ‘care, anxiety, sorrow,’ from the equivalent Middle High German sorge, Old High German soraga, feminine, whose Franconian variant sworga makes it probable that the word was derived from an Aryan root swerk (to which Old Irish serc, ‘love,’ is allied?) or Aryan swergh (compare Lithuanian sergéti, ‘to guard’). Yet the forms in the other Teutonic dialects have not the w; compare Gothic saúrga, Anglo-Saxon sorh, English sorrow, Dutch zorg, Old Saxon sorga. Nothing certain can be asserted concerning the early history of the word.