The Two Towers by J.R.R Tolkien (Harper Collins 1991, 2007) pp. 668-671
As Gandalf and his companions enter the hall of Théoden Tolkien gives us many contrasts. The light of the sun falls only upon the image of Eorl the Young while everything else is in cloying darkness. A man sits upon a gilded chair “so bent with age that he seemed almost a dwarf; but his white hair was long and thick and fell in great braids from beneath a thin golden circlet set upon his brow.” This man has a beard that reaches his knees “but his eyes still burned with a bright light”.
In other words we are meant to see that the decline of the House of Eorl is only superficial. There is a potency within Rohan that now lies hidden but could be unveiled in a moment. Gandalf knows this and appeals to Théoden to join the conflict against Sauron.
But there is one other person who is, perhaps, more aware than any of the hidden power of Rohan and that is Grima, Wormtongue, the King’s chief counsellor. He has long been secretly in the service of Saruman ever working to weaken the resistance of the Rohirrim against his true master, ever weakening the resolve of Théoden to resist him. When Saruman was not at open war against Rohan it was easy to convince Théoden that he posed no threat. But when open war began Wormtongue’s task became more difficult. Now what he sought to achieve was to weaken Théoden’s resolve and to convince him that his only hope lay in keeping the larger part of his force within Edoras so that in the battle at the Fords of the Isen where Théodred, Théoden’s son fell in battle, his armies were insufficient in number to mount an effective defence. And, perhaps worst of all, the King of Rohan was sitting upon a chair in his darkened hall while his people were falling in battle vainly seeking to defend their homes.
In his guise as the Grey Pilgrim Gandalf has always sought to achieve his purpose by encouragement and persuasion. He has never used force except by necessity. He has remained true to the charge that the Istari, the wizards, were given by the Valar not “to reveal themselves in forms of majesty, or to seek to rule the wills of Men or Elves by open display of power” (Unfinished Tales p.389). As the secret keeper of Narya the Red, one of the three Elven Rings forged by Celebrimbor he has sought to kindle hearts and not to dominate them. But now the great crisis of the Third Age of Arda has come. There is no longer the time to work in this way. in time past Gandalf had been willing to accept rejection patiently, to withdraw from Edoras as he did upon Shadowfax after his escape from Isengard, but now there is no time to act in this fashion. Saruman is at open war with Rohan and, worst of all, so is the Dark Lord in Mordor.
And so in this moment when a choice must be made Gandalf casts aside his tattered cloak and reveals himself in power.
“The wise speak only of what they know, Grima son of Gálmód. A witless worm you have become. Therefore be silent, and keep your forked tongue behind your teeth. I have not passed through fire and death to bandy crooked words with a serving-man till the lightning falls.”
There is a particular kind of wisdom required to know the true moment of crisis when all normal forms of action must be cast aside and replaced by decision. Some are too quick to do this and so act too soon. Gandalf knows that patient diplomacy is now insufficient, that if Rohan remains passive it will fall, so too will Gondor, and ultimately so will all the free peoples of Middle-earth and so night will fall. Gandalf has passed through his own personal crisis in his battle against the Balrog of Moria that ended with his death and so no longer fears anything less than that. He must rouse Théoden from his illusion of decrepitude and with the King restored to who he truly is so too will the Rohirrim rediscover their greatness.
Reminiscent of Glorfindel at the Ford of Bruinen, revealing himself “as he is upon the other side, one of the mighty of the Firstborn” (Gandalf’s words), at a moment of crisis. So the Elves, too, are circumspect about displaying and using their power.
And Glorfindel was unusual, even among the Elves of Middle-earth as being one who knew Valinor. I am also reminded, thanks to your reference, to the story of Moses having to hide his face after seeing the glory of God.