Short answers, pulled from the story.
Immanuel Kant was a German philosopher born in Königsberg on the 22nd of April 1724 and considered one of the central thinkers of the Enlightenment. His systematic works in epistemology, metaphysics, ethics, aesthetics, and political theory made him one of the most influential figures in modern Western philosophy.
The Critique of Pure Reason, first published in 1781 and revised in 1787, argues for transcendental idealism, the doctrine that space and time are mere forms of intuition that structure all experience. It claims we have knowledge only of appearances, not of things in themselves, and frames its project around the question of how synthetic judgments a priori are possible.
The categorical imperative is Kant's principle that all moral obligation binds rational agents regardless of their desires. One formulation directs a person to act only on a maxim they could will to become a universal law, and another commands treating humanity always as an end and never merely as a means.
Immanuel Kant died in Königsberg on the 12th of February 1804. His health had long been poor, and he reportedly said Es ist gut, meaning It is good, before his death.
Kant laid out the nebular hypothesis in his 1755 Universal Natural History and Theory of the Heavens, deducing that the Solar System formed from a large cloud of gas. He correctly reasoned that the Milky Way is a disk of stars and suggested that distant nebulae might be other galaxies.
In 1792 the King's censorship commission blocked part of Kant's Religion within the Bounds of Bare Reason. After he published a second edition in 1794, a royal order forbade him from publishing or speaking publicly about religion, and he responded in the preface to The Conflict of the Faculties in 1798.