Nearly a hundred years ago, there was a really bitter debate about the right interpretation of Kant. There was the Marburg school, and opposed to it was Leonard Nelson. That is the Kant-Fries School.. I have to admit I think that Nelson was right, but the bitterness of the debate surprises me. The simplest way to understand it is the concept of immediate non intuitive knowledge. That is, things that you know not through any thing but direct awareness. And also not through the senses. My own feeling about this is more or less is this: I looked at the friesian.com web site of Kelley Ross. and was astonished at his insights--so I more or less decide to follow that point of view even though other Kantian school, also had some good points. You might wonder what is the need for Kant? After all Musar [Medieval Ethics ] is already a perfectly good synthesis between Torah and Plato/Aristotle. The reason is mainly because of some good points that were raised by Descartes that no one answered very well until the Kant Fries approach came along.