I shared information.
My father did the same. And his father, and his father before him.
That is how we increase our knowledge.
Those of Eltnam do not take their knowledge from books, but from other humans.

That is the result of a rational pursuit of knowledge.
If you want to know something, you don't necessarily have to study just that one thing.
It is more efficient to copy the knowledge of someone who has studied it and more. Then you will have the whole of his knowledge, not just one piece of it.
So thought our ancestors, who created the means by which we can read data directly from the human mind.
Using the Etherlite, the artificial nervous system constructed of ether, hacking into the soul is possible.

When the Etherlite touches another human being, it merges with their nervous system and links their mind with that of the user.
You might say it takes over that person's hardware.
Thought directs the body; and ordinarily, the brain is its only control center.

The Etherlite hacks into this process and becomes a second control center, sabotaging the original. It hacks orders to the body, which believes they came from its own brain.
The Etherlite penetrates to the deepest level.
From the brain, it takes information.
It creates a blueprint of the soul from which thought processes are derived.

Of course, to completely seize someone requires the breach of reason, instinct...... thousands of barriers.
It truly is a talent.
With this ability to invade the information of others, the House of Eltnam can overcome any obstacle with ease.
The target has no choice but to yield their knowledge.
Other powerful methods of collecting a person's knowledge; drugs, the hypnotic gaze of a vampire... those methods can damage the information so that perfect playback is impossible. Certainly, they damage the target itself.

But our method is different.
Our way does not leave a scar in the mind. Thoughts are invaded, downloaded, and even rewritten without the person being aware.
Even morally bankrupt alchemists consider this heresy.
So Eltnam kept its great power a close secret.