a theory is Celestia also had a mane 6..... they where just forgotten... if you could recall there are statues of ponies beside discord... those might be celestia's mane 6. 

so in twilight's case.... the mane 6 is forgotten and twilight is the only symbol left like Celestia. and again Discord is forgotten again. the mean 3 aswell. and other stuff....

Henryk is Argyle-like: "In reality his failures were so continuous that they were wonderful, and might easily drive a nail into the head, especially of the man who had experienced them"

"The lens of the lantern cast into the darkness an enormous triangle of light, beyond which the eye of the old man was lost in the black distance completely, in the distance mysterious and awful. . But that distance seemed to run toward the light. The long waves following one another rolled out from the darkness, and went bellowing toward the base of the island; and then their foaming backs were visible, shining rose−colored in the light of the lantern. The incoming tide swelled more and more, and covered the sandy bars. The mysterious speech of the ocean came with a fulness more powerful and louder, at one time like the thunder of cannon, at another like the roar of great forests, at another like the distant dull sound of the voices of people. At moments it was quiet; then to the ears of the old man came some great sigh, then a kind of sobbing, and again threatening outbursts. At last the wind bore away the haze, but brought black, broken clouds, which hid the moon. From the west it began to blow more and more; the waves sprang with rage against the rock of the light−house, licking with foam the foundation walls... Outside, people on those ships were struggling with night, with darkness, with waves; but inside the tower it was calm and still."

"The light−house had become for Skavinski such a half grave. Nothing is more monotonous than life on a beacon− tower." ... "The distant views repaid him for the poverty of the island, however."  "Moreover, he had become a mystic; his mild blue eyes began to stare like the eyes of a child, and were as if fixed on something at a distance."

Henryk finalises his transformation into Sunny-Twiligjht: "The package, cut open, lay before him, shone upon clearly by the afternoon sun, and on it was an open book. When the old man stretched his hand toward it again, he heard in the stillness the beating of his own heart. He looked; it was poetry"

And then he returns to the land of his memory :3 just like Argyl. 

I loved the description of the Sea and also the description of loneliness. Argyll is definitely lonely - he is depicted as the only pony who truly remembers his pony heritage, similarly to Henryk's sad realisation, as an old man, that he has been haunted by memories of his homeland, only to reach out for it too late. If only Henryk had had a daughter  

@abrony-mouse So you did actually read the story? That's impressive. I admit I did not remember it very well, so I re-read it, and now I'd write this entry a bit differently. "Vast knowledge about the old times of glory" is not a good way to describe it, it was just great longing deep inside him that waited for an opportunity to reveal itself. But the analogy to Argyle still stands. While technically he was still in Equestria, it wasn't the same place as it was in the times of friendship and magic, and the longing was strong within him as well. As you pointed out, the difference is that he had a daughter, and through her he hoped to restore things to the way they should be. Too bad he didn't live to see it himself...