lykill ‘key’: Only occurrence in skaldic poetry. The Cross as key is a fairly common image, based primarily upon the ‘key of David’ in Isa. XXII.22 and Rev. III.7. See, e.g., Augustine, Enarrationes in Psalmos XLV (Augustinus Hipponensis, col. 514) crux Domini nostri clavis fuit, qua clausa aperirentur ‘the Cross of our Lord was a key by which closed things were opened’ and Bonaventure ipsa crux ... comparatur et assimilitatur in Sacra Scriptura clavi domus David ‘the Cross itself is compared and in holy scripture likened to the key of the house of David’ (Bonaventure 1882-1902, IX, 222). The image is also found in Cross hymns, often, as here, with specific reference to opening heaven: e.g. Ave, clavis reserans / Portas paradisi / Adam quas exasperans / Clausit ‘Hail, key, unlocking the gates of Paradise, which Adam, making them harsh, closed’ (AH 38, 88, cf. 128; 40, 33; 8, 30); see also Gimsteinn 111/1 Hægur lykill himna ʀikis ‘convenient key of heaven’ (ÍM I.2, 329).