This is Volume IV in The Complete Works of Immanuel Kant from LP.
The Prolegomena was published two years after the first edition of the Critique of Pure Reason and summarizes the Critique's essential arguments utilizing phraseology and lines of though not present in the first edition. This was intended by Kant as a simplified and clear presentation of the Critique, and he would later work some of these summaries back into later versions of the Critique. It is a hostile polemic against the initial criticisms from specific authors and broadly against the Empiricism of Deterministic Causality and attempts to charta an Ontotheology based on the internal ordering of the mind and soul. Here he returns to the basic ideas of his Metaphysics and lays the foundation for a Metaphysical science that is as respected as mathematics or physics.
Just like the Critique, the Prolegomena is Epistemological in nature, focusing on questions on the perception and acquisition of knowledge. Kant muses on a range of Cosmological and Noetic questions, such as how are a priori assumptions possible, or how is knowledge from pure reason possible? How is our numinal consciousness structured, and how does it know the world? What is Space, time, and the cosmos, and how does God interact with or is known by the material world and its inhabitants?