Baptized Emanuel Kant (he changed the spelling of his name later in life), Kant was born in 1724 in eastern Prussia (present-day Germany); his hometown, Konigsberg, in now part of Russia. As a boy, he was a good student who received a strict religious education that emphasized the literal interpretation of the Bible and fluency in Biblical languages over liberal arts subjects like science and history. When his family recognized his scholarly aptitude, he was sent to school, eventually attending the University of Konigsberg, where he was introduced to German and British philosophy, science, mathematics, and the advances in physics recently introduced by Isaac Kant. After his father suffered a stroke, Kant supported his family by working as a tutor, and continued to pursue his studies in his free time.
In 1749, at the age of 25, he published his first work, Thoughts on the True Estimation of Living Forces, a direct outgrowth of his university studies in which he defended a position of metaphysical dualism while arguing against the beliefs of many of his contemporary German philosophers. Other works followed, in both philosophy and science (a distinction not made as sharply in the 18th century as it is now). Interestingly, although Kant is now thought of as one of the more difficult and esoteric German philosophers whose work is full of complex concepts, one of his early contributions was the Nebular Hypothesis. In 1755's Allgemaine Naturgeschichte, rarely translated into English because it is now of interest principally to historians of science, Kant refined Emanuel Swedenborg's 1734 hypothesis that the solar system had begun as a cloud of gaseous material which condensed into the "clumps" of the sun and planets. Kant concluded that in order for this cosmological model to work, those clouds--nebulae--must rotate, with gravity gradually crunching them down into the solid state of the solar system. This remains the most widely accepted cosmological model today, with modifications and tweaks due to our expanding view of the universe. What's fascinating is that Kant (and Swedenborg) were able to come to this conclusion hundreds of years before satellites, probes, and other tools of modern astronomy.
In that same year, Kant moved on from his tutoring job to become a more highly paid and respected university lecturer. Throughout his thirties, he wrote a variety of philosophical texts dealing with logic, emotion, and the existence of God. At the age of 45, he was made a full professor of logic and metaphysics at Konigsberg, becoming caught up both in that work and in the response to his written work so far--consequently, he didn't publish again for eleven years. When he finally did, the result was Critique of Pure Reason, the most impressive work of philosophy by a single author--though perhaps because of its immense size, or possibly because Kant had been silent so long, it had little immediate impact.
The first of Kant's "three critiques," Pure Reason is difficult to sum up. He begins by rejecting the recent conclusions of his friend and fellow philosopher David Hume, whose work argued that ideas all begin as representations of sensory (i.e. physical) experience. Kant claimed that we could have knowledge not based on empirical experience--indeed, that much important and applicable knowledge had begun as such--and spent 800 pages proving his argument. The book is dense, filled with thought experiments and specialized language that doesn't translate well into English.
The work rejuvenated Kant�s interest in publishing, or maybe just cleared his throat so he could get back to it. The 1780s were a busy time for him, with the publication of his first works on moral philosophy as well as his second and third critiques (Critique of Practical Reason and Critique of Judgment). Naturally, he attracted a good deal of criticism but his influence was undeniable, and the school of German Idealism formed among his pupils and younger colleagues. A true workaholic, he never married. He did, however, have a big following; when he died shortly before his 80th birthday, having published regularly until the last year of his life, he was mourned by many.
