There is no single lesson to derive from the Numenor parable; a true myth is not an allegory but a sub-creation with a life of its own.
But Tolkien's version of the Atlantis theme (deriving from Plato's dialogues Timaeus and Critias, and long regarded as, at least, semi-historical) is something I find ever-more resonant.
Numenoreans were the minority of mortal Men who had fought alongside Elves and Valar to overthrow the evil god Morgoth.
As a reward and compensation for destruction of their lands; by the gods these Men were given peace and plenty, their bodies were enhanced in strength and stature, they were freed from bodily
suffering and illness, they were given a beautiful and safe island in which to
dwell - out of reach of Middle Earth, their intelligence and skill were enhanced - including the use of magic, they had the
friendship and help of the High Elves.
Their life span was extended about threefold, so they would have enough time to bring their schemes to fruition.
The Numenoreans were thus made super-Men; but they remained Men: mortal Men.
And for all their enhancements they had the faults of Men.
What did they do - what did they make of their opportunities?
For a while
they were satisfied to live well - enjoying the simple things of human
life enriched by disinterested learning, art, and religion - and
faithfully accepted death when it was due...
became scholars, scientists and technologists; almost matching the High Elves in
their ingenious devices; and surpassing them in becoming the greatest mariners the world had seen, the
greatest military power...
For a while.
soon they got bored, felt constrained, wanted a change, wanted power and wealth and luxury and to dominate, wanted the worship and subservience of lesser men -
wanted all this and nothing less than than all this; here, now and forever.
Wanted perfect satisfaction of all their desires: Good and evil.
Wanted permanent worldly gratification.
rejected beauty for power, science for magic, rejected truth and freedom for propaganda
and totalitarian coercion, disbelieved in the virtue of the one God and
his Valar - eventually, in a final rapid spiral-down into the pit,
embraced the worship of 'the dark lord' Morgoth and the High Priest status of Sauron, because they believed he
could grant them their desires.
Other Men of Middle Earth then feared them; they were terrorized, exploited, enslaved, sacrificed.
Sensing their own
degeneration and decline, ignoring argument, refusing repentance; the
Numenoreans built a massive armament and assaulted the gods by force, invaded the undying lands to
take what they wanted - to be immortal gods on earth...
And by direct act of The One (Eru, God); the invading army was destroyed, Numenor itself was destroyed, all its people were destroyed (except for a small surviving minority resident in Middle Earth or swept there in ships) by a
cataclysmic remaking of the world.
In grasping at gratification of all their desires and forever, they embraced destruction: nihilism.
Numenor is modern man, conceptualized as being enhanced in both individual and social capability but failing to use these
gifts for spiritual purposes; and instead pursuing more and ever-more
personal and material goals, never satisfied, insatiable - grasping
at more life, more power, more pleasure; at first with energy and zeal,
then with fear and exhaustion, finally with despair and insane
renewal was possible for Numenor at any moment up until the last moment - they were given chance after chance. The
gods and The One held back their justice until they had no choice but to
But repentance was always blocked by pride.
At the end, the
Numenoreans were, as a culture, insane, having embraced insanity by incremental steps,
until - I guess, perhaps - the clearing of illusion at the very end. At
the very end when utter failure was obvious and imminent, it is likely that
death and destruction, annihilation, was actually chosen.
Chosen on the same basis that Denethor (one of the last true Numenoreans) described in his despair:
"...if doom denies this to me, then I will have naught:
neither life diminished, nor love halved, nor honour abated. (...) But
in this at least thou shalt not defy my will: to rule my own end."
Thus is pride the strongest of sins, thus is damnation chosen at the last.