Let it be the Second Preface to his Critique of Pure Reason. CPR is Kant’s foundational and most important work. Yet it’s long and complicated. When he published the second edition in 1787, he took pains to write a new preface outlining his main conclusions, his reasons for them, and their key implications for future philosophy. And it’s only 12 pages.
Suggested primary and secondary sources:
Here is the text of Kant’s “Second Preface” itself: PDF.
Here is my primer close-reading of the text: Video.
Here is a scholarly article by me on its relevance for the Is-Kant-objectivist-or-subjectivist debate: PDF.
Here is my book-length discussion of Kant’s intellectual-history significance on the road to postmodernism: Text or Audiobook
Here is how Kant’s Critique of Pure Reason works with his later Critique of Judgment and their joint influence on modernist and postmodernist art: Video Interview.
Related: Philosophers, Explained series on the great philosophers and their major works..