An Etymological Dictionary of the German Language/Annotated/Sache
Sache, feminine, ‘thing, matter, affair, business, case,’ from Middle High German sache, Old High German sahha, feminine, ‘quarrel, cause of dispute, lawsuit, opportunity, affair, cause, reason'; corresponding to the equivalent Old Icelandic sǫk, feminine, and Old Saxon saka, feminine; compare Dutch zaak, ‘thing,’ Anglo-Saxon sacu, ‘strife, feud,’ English sake, Gothic sakjô, feminine, ‘strife, dispute.’ The cognates are connected with Gothic sakan, ‘to strive, dispute,’ Anglo-Saxon sacan, Old Saxon sakan, Old High German sahhan, ‘to blame, scold; sue (at law).’ The root sak, ‘to contend, sue (at law),’ is peculiar to Teutonic. The evolution in meaning is worthy of special notice. The general sense ‘case' is a later development of ‘lawsuit, dispute,’ which has been preserved in Modern High German Sachwalter, ‘attorney, advocate’ (see further Widersacher). Old legal parlance developed the former from the latter.