There is something profoundly insightful about Kant's idea that we really do no understand "things in themselves" This was originally derived from John Locke that noticed that some traits are in things in themselves and others are how we react to them. E.g. how they feel our touch. Kant noticed that even trait that we think of as being in things in themselves are really what we add to them. So if you abstract these traits then what is the thing in itself? We do not know. You see this in Physics.  One one hand Physics recognizes mass and charge as very well understood and measurable in the lab. But  as Kant would that that is how we interact with the mass and charge of the electron. But the "bare mass"? The mass that you calculate in the sum of the kinetic energy and potential energy? That bare mass in infinity.  It is hard to understand how the electrons mass can be infinity. So Kant was right that we really do not understand things in themselves. [The "bare mass" is one of the many famous infinities that come up in Quantum Field Theory. Richard Feynman sort of solved the problem by what is called normalization but it is more like sweeping the dust under the rug]