Missing the Point

"... Einstein was smart enough to recognise that the non-aether theories were more elegant and simpler, but he made the mistake of rejecting it on the grounds that 'what is unobservable does not exist'. Le Sage, on the other hand, he was smart, he was on the right track. Those ultramundane particles were-"
"Sir? What's this got to do with the Dream? I mean, why do we have to know about these scientists from other realities and what's it got to do with the Dream?" Lacier asked, hoping that his interruption would not give him something to regret.
Mr. Ary looked at him and said, his mouth moving all around his face. "As I was about to explain, Mister Eves, these ultramundane particles spread across realities and dimensions to cause disturbances on the aether-affected subconscious of the mind, giving rise to anomalies within the Dream. Do not interrupt me further, or your time will be consumed by needless amounts of work."

Hardly anyone dared to say anything during Mr. Ary's class. Anyone who had ever seen him would know why. Mr. Ary was horrifying, his features were liquid and regularly sunk back into his face and reappeared. His features also had a disturbing tendency to shift across his face, at any point of time, his eyes could be on his cheeks, on the chin, on his hand, on the back of his head (Mr. Ary was bald) and just about anywhere. The same went for his other features such as his nose, eyebrows, mouth and all. He had no need to turn while talking, he just had to move an eye back around. All in all, it contributed to his fearsome reputation of ineffability. No one knew how he got to this state, no one wanted to know, not even the morbidly curious.

"Eigengrau. Who can tell me what Eigengrau is?" He asked. "You, over there."
"It's the color that we see in pitch darkness, sir." Cocytus answered. "The brain places a greater importance on contrast rather than colour so eigengrau appears a shade lighter than a black object."
"Good. Now we'll...." The day went on. And finally, the lesson ended.

Lethe picked up her courage and slowly made her way to the unnerving teacher while her classmates filed out.
"Yes? You have lessons to attend." Mr. Ary said sharply.
"No sir, its Halflight. Uh, sir? I've been having this nightmare recently." She said, looking at his shifting eyes.
He sighed. "What is it? This had better not been a frivolous waste of my time."
She told him about her dream, haltingly, hoping that he could shed some light. By the end of the tale, she had his full attention and all his features were, for the first time, in proper place and not moving. He rubbed his brow.
"Lethe. You know I cannot tell you, until you know what to say."
"What?" Lethe said, startled by his reply. "What do you mean?"
"You're not there yet, are you? When you know what to say, come back and find me and I'll explain it all to you."
"I don't get it sir, I don't understand. Why can't you tell me?"
"Of course, you don't remember. All you need to know for now is that I can't tell you because of the deal we made. Come back when you know what to say."
Lethe stared at him. "Deal? I've never ever seen you before in my whole life prior to today! Sir, I-"
"I will say nothing more until you know what to say. Do not forget to do your work, gravitational aether theories will be tested soon." With that, Mr. Ary strode off out of the classroom.
Lethe? A voice echoed in her mind. It was Styx. We're waiting for you. What did he say?
Only some weird cryptic thing about a deal we made. She thought back. It's ridiculous. I'm on my way, tell you all about it later.