So what Kain wanted to emulate was just "the impure self" part.
However, this only lowers the difficulty from impossible to extremely difficult.
This "the himpure self" contains an incredibly large amount of information, not just the contribution of thoughts, but literally all external stimuli.
From the small things like the temperature our skin feels at any given moment, or whether the sun is warm enough today, to things with a bigger impact like social relationships.
That is how the impure self is built every day, until the day we die.
Of course, Kain didn't intend to simulate it perfectly, he just needed to simulate it to a certain level enough for him to be able to perform basic magic.
But Kain was not sure when "enough" would ever be enough. He can only try.
And the subject that Kain chose to simulate was Alisa.
