An Etymological Dictionary of the German Language/er

by Friedrich Kluge

er, pron., ‘he, it,’ from MidHG. and OHG. ër, corresponding to the equiv. Goth. is, from a pronom. stem of the third person i-; comp. Lat. i-s (Lat. id, Goth. ita, OHG. and MidHG. ëȥ, ModHG. es). Akin to the Sans. pronom. stem i-.