Kant's metaphysics, as elucidated in his Critique of Pure Reason, is generally referred to as transcendental idealism. One of the essential ideas of the work is the idea of transcendental apperceptions, the a priori intuitions which condition our thought processes, creating, for example, the categories of space and time.
This gets interesting when we consider that fundamentally, if we accept this idea, we are forced to admit either that these concepts in-themselves are what make experience itself possible or our experience actually makes these concepts possible. Kant's position arguably requires radical subjectivity, for the "world of appearances" which presents itself to our senses is, for our purposes, the only reality which our transcendental apperceptions will permit to manifest from the noumenal reality-in-itself, which can be known only by pure reason.
Kant's position with regard to morality was that the moral faculty itself was the effective agent of free will which distinguished man as a reasoning and thinking being from being possessed simply of a reactive cognition. This participation in the intelligible world was in effect his spiritual and immortal part, his connection to Deity, as distinguished from his immersion in the existential sense-world of animal nature. For Kant, man's essential ground is in the being of Consciousness rather than in that of "mere" existence.
The CoPR is a monolithic text which is widely considered to be among the most difficult books ever written (so much for eloquence!).
To get a better handle on the concepts, it might prove helpful to consider the Neoplatonic roots of Western philosophy as Kant probably learned it, as well as to consider the similarities and differences between his categories, Jung's Archetypes, and the Sephira of the modern Qabalists, to get an idea, from a less formal perspective, of the real scope of his thought - or rather, his early attempt at a scientific metaphysics. Regardless of the academic correctness of doing this, it should provide some interesting coincidences.
The preceding is from memory, and the paragraph above contains my own speculations. I apologize for any inconsistencies or outright mistakes (and promise to mend my ways).