What did Immanuel Kant do that he is most famous for?
In simple terms, Kant pointed out that we all shape our experience of things through the filter of our mind. The mind shapes that experience, and among other things, Kant believed the concepts of space and time where programmed into the human brain, as was the notion of cause and effect. We never have direct experience of things, the noumenal world, and what we do experience is the phenomenal world as conveyed by our senses. These observations summarize Kant's views upon the subject–object problem.