An Etymological Dictionary of the German Language/schauen
schauen, vb., ‘to look at, gaze,’ from MidHG. schouwen, OHG. scouwôn, ‘to see, look at, contemplate’; comp. OSax. scauwôn, Du. schouwen, AS. sceáwian, ‘to look at’ (whence E. to show); Goth. *skaggwôn is wanting, to this usskawjan, ‘to restore to consciousness.’ From the root skau, skū̆, ‘to see’ (see schön), are also derived Goth. skuggwa, m., ‘mirror,’ OHG. scû-char, ‘mirror,’ further OHG. scûwo, AS. scûa, OIc. skugge, m., ‘shadow’ (see Spiegel); also OIc. skygna (Goth. *skuggwinôn), ‘to spy,’ skyn, n. and f., ‘perceiving,’ skoða, ‘to spy.’ In the non-Teut. languages, Sans. kavis, ‘sage, poet,’ Lat. cavere, ‘to beware,’ Gr. κοέω, ‘I mark,’ OSlov. čują, čuti, ‘to be sensible of, feel, perceive,’ are also connected with the root skū̆, skau, or rather kū̆, kau.