No More Learning

' and so left him bruised
And battered, and fled on, and hill and wood
Went ever streaming by him till the gloom,
That follows on the turning of the world,
          the common path: he twitched the reins,
And made his beast that better knew it, swerve
Now off it and now on; but when he saw
High up in heaven the hall that Merlin built,
Blackening against the dead-green stripes of even,
'Black nest of rats,' he groaned, 'ye build too high.