Good things of day begin to droop and drowse

Of course it doesn't matter that Shakespeare almost certainly didn't know this: it still gives me pleasure that a couple of his most beautiful lines ('Light thickens; and the crow/Makes wing to the rooky wood' [lines 50-51]) play so neatly with the Old Norse word rökr ('dusk', 'twilight').

The closeness of this latter to rök, 'destiny' (as in Ragnarök, 'the destiny of the Gods') led to some Old Norse authorities confusing it with, and indeed changing it to Ragnarökr: 'the twilight of the gods'. Hence the whole Wagnerian, Götterdämmerung vibe, so fitting to a consideration of Macbeth.