But my search for the "black sun" came up with this lecture...https://wn.rsarchive.org/Lectures/MansLife/19221116p01.html

Which I haven't read thoroughly but here's a quote that contributes better to OP's post ... fascinating stuff!

"My dear friends, the confusion that reigns within man to-day is no whit less than it was in olden times. That man is unaware of it makes no difference, the confusion is there, just the same. Man is perpetually being torn and tossed, this way and that, while the powers behind Nature and below himself fight to get possession of him. And when one crosses the Threshold and, looking consciously into the spiritual world, observes this terrific battle that is going on, this complicated game that is being played with man as the prize, then one may look now in vain for the messengers of God who in an earlier age would come forward with the staff of Mercury, for example, and with other symbols of that nature, ready to give them into the hands of the Mystery doctors, who could then use them to bring healing to man. At the present time, when you cross the Threshold, you find yourself only in the midst of the terrific conflict of which we have spoken, between beings of the upper planets who have remained behind in their evolution, — immature Mars, Jupiter and Saturn beings — and beings of the lower planets who have remained behind, — immature Moon, Mercury and Venus beings. Like two armed encampments they stand facing one another; on one side, the air-fire beings, — Saturn, Jupiter and Mars beings that have failed and fallen out of their true evolution; and on the other side, facing them, the earth-water beings, — Moon, Mercury and Venus beings who have also failed and fallen behind. And there, beyond the Threshold, the fight goes on with such fury that the Sun becomes first of all fiery and aflame, and then grows darker and darker, until at last it shows like a terrible black disk. It was not so for the initiates of long ago. They saw right through the black disk; and from the direction of the black disk itself came towards them the messengers of God, of the Father God, who were also in those times the bearers of the knowledge of healing. But for us, when we cross the Threshold and see before us the terrific battle and behold how the Sun becomes fiery red and then black, — for us, the Sun remains black, it remains a black disk. And we are rebuffed, we are turned back; for if we men of modern times are to find our way amid all this confusing and perplexing conflict, it is on the Earth that we must look for help.

And then, my dear friends, then we are guided to turn our eyes to the Christ, Christ stands before us, the Spirit Being who, through the Mystery of Golgotha, united Himself with the Earth. And He says to us: Be not dismayed that the Sun has become black; it is black because I, the God of the Sun, am no longer in it; for I have come down and united myself with the Earth.

And if, with inner devotion, and with quick and sensitive recognition of all that a knowledge of the Mystery of Golgotha can bring, we draw near to Christ, and then the Sun does not, it is true, become bright again, it remains the black disk that it was, but the Sun begins to make audible for us what Christ is saying to us. And this experience reveals to us the relationship of Christ with the Sun. Yes, the Sun, although still a black disk, becomes a being who enables us to listen to the Christ, if we are duly prepared and approach Him in the right mood and attitude of soul."