The Magna Carta of 1215. This document is now held at the British Library
Source Wikimedia Commons
 
And still when mob or Monarch lays
Too rude a hand on English ways,
The whisper wakes, the shudder plays,
Across the reeds at Runnymede.
And Thames, that knows the moods of kings,
And crowds and priests and suchlike things,
Rolls deep and dreadful as he brings
Their warning down from Runnymede!
 
From Rudyard Kipling’s What Say the Reeds at Runnymede?