Authorial high-jinks on the slopes of Mount Doom

As we've seen before, Tolkien is hardly averse to slipping a bit of humor or even (gasp!) irony into his writing. We might not expect it on the slopes of Mount Doom, however.

And far away, as Frodo put on the Ring and claimed it for his own, even in Sammath Naur the very heart of his realm, the Power in Barad-dur was shaken, and the Tower trembled from its foundations to its proud and bitter crown. The Dark Lord was suddenly aware of him, and his Eye piercing all shadows looked across the plain to the door that he had made; and the magnitude of his own folly was revealed to him in a blinding flash, and all the devices of his enemies were at last laid bare. Then his wrath blazed in consuming flame, but his fear rose like a vast black smoke to choke him. For he knew his deadly peril and the thread upon which his doom now hung. 

(RK 6.iii.946, emphasis mine)

Sauron's discovery of what a fool he's been is apocalyptic both literally and metaphorically, and I would be hard-pressed to say which sense predominates. The Greek verb from which apocalypse and apocalyptic derive -- ἀποκαλύπτω -- means quite simply 'to reveal', as in 'the magnitude of his folly was revealed to him'. The New Testament book known in English as Revelation is called Ἀποκάλυψις (Apocalypsis) in the Greek original. Metaphorically, of course, it has been used for well over a century to mean: 

'Of, relating to, or characteristic of a disaster resulting in drastic, irreversible damage to human society or the environment, esp. on a global scale; cataclysmic.' 

(OED)

 That same sentence also recalls the moment thousands of years before, which Gandalf spoke of in The Council of Elrond:

For in the day that Sauron first put on the One, Celebrimbor, maker of the Three, was aware of him, and from afar he heard him speak these words, and so his evil purposes were revealed. 

(FR 2.ii.253)

and

Out of the Black Years come the words that the Smiths of Eregion heard, and knew that they had been betrayed: 

   One Ring to rule them all, One Ring to find them,
   One Ring to bring them all and in the Darkness bind them.

(FR 2.ii.254)

The irony here is nothing short of precious.

Finally there's the 'blinding flash' which paradoxically allows Sauron to see, which it is tempting to see as an allusion to Amazing Grace, except that in Tolkien's time Roman Catholics and Protestants were rather less ecumenical with their hymns than they have since become. Then, too, Amazing Grace seems to have been far better known in the US than it was in the UK, where it only became popular in the 1950s and was first published in a hymnody in the 1960s. So, we had better regard this as unlikely to be an allusion, though not impossible.