At age 46, Kant was an established scholar and an increasingly influential philosopher, and much was expected of him.
In correspondence with his ex-student and friend Markus Herz, Kant admitted that, in the inaugural dissertation, he had failed to account for the relation between our sensible and intellectual faculties.
He needed to explain how we combine what is known as sensory knowledge with the other type of knowledge—i.e.
reasoned knowledge—these two being related but having very different processes.

Kant also credited David Hume with awakening him from a "dogmatic slumber" in which he had unquestioningly accepted the tenets of both religion and natural philosophy.
Hume in his 1739 Treatise on Human Nature had argued that we only know the mind through a subjective—essentially illusory—series of perceptions.
Ideas such as causality, morality, and objects are not evident in experience, so their reality may be questioned.
Kant felt that reason could remove this skepticism, and he set himself to solving these problems.
Although fond of company and conversation with others, Kant isolated himself, and resisted friends' attempts to bring him out of his isolation.
When Kant emerged from his silence in 1781, the result was the Critique of Pure Reason.
Kant countered Hume's empiricism by claiming that some knowledge exists inherently in the mind, independent of experience.
He drew a parallel to the Copernican revolution in his proposal that worldly objects can be intuited a priori ('beforehand'), and that intuition is consequently distinct from objective reality.
He acquiesced to Hume somewhat by defining causality as a "regular, constant sequence of events in time, and nothing more."

Although now uniformly recognized as one of the greatest works in the history of philosophy, this Critique was largely ignored upon its initial publication.
The book was long, over 800 pages in the original German edition, and written in a convoluted style.
It received few reviews, and these granted it no significance.
Kant's former student, Johann Gottfried Herder criticized it for placing reason as an entity worthy of criticism instead of considering the process of reasoning within the context of language and one's entire personality.
Similar to Christian Garve and Johann Georg Heinrich Feder, he rejected Kant's position that space and time possessed a form that could be analyzed.
Additionally, Garve and Feder also faulted Kant's Critique for not explaining differences in perception of sensations.
Its density made it, as Herder said in a letter to Johann Georg Hamann, a "tough nut to crack", obscured by "all this heavy gossamer".
Its reception stood in stark contrast to the praise Kant had received for earlier works, such as his Prize Essay and shorter works that preceded the first Critique.
These well-received and readable tracts include one on the earthquake in Lisbon that was so popular that it was sold by the page.
Prior to the change in course documented in the first Critique, his books had sold well.
Kant was disappointed with the first Critique's reception.
Recognizing the need to clarify the original treatise, Kant wrote the Prolegomena to any Future Metaphysics in 1783 as a summary of its main views.
Shortly thereafter, Kant's friend Johann Friedrich Schultz (1739–1805) (professor of mathematics) published Erläuterungen über des Herrn Professor Kant Critik der reinen Vernunft (Königsberg, 1784), which was a brief but very accurate commentary on Kant's Critique of Pure Reason.

Kant's reputation gradually rose through the latter portion of the 1780s, sparked by a series of important works: the 1784 essay, "Answer to the Question: What is Enlightenment?";
1785's Groundwork of the Metaphysics of Morals (his first work on moral philosophy); and, from 1786, Metaphysical Foundations of Natural Science.
But Kant's fame ultimately arrived from an unexpected source.
In 1786, Karl Leonhard Reinhold published a series of public letters on Kantian philosophy.
In these letters, Reinhold framed Kant's philosophy as a response to the central intellec
At age 46, Kant was an established scholar and an increasingly influential philosopher, and much was expected of him. In correspondence with his ex-student and friend Markus Herz, Kant admitted that, in the inaugural dissertation, he had failed to account for the relation between our sensible and intellectual faculties. He needed to explain how we combine what is known as sensory knowledge with the other type of knowledge—i.e. reasoned knowledge—these two being related but having very different processes.
Kant also credited David Hume with awakening him from a "dogmatic slumber" in which he had unquestioningly accepted the tenets of both religion and natural philosophy. Hume in his 1739 Treatise on Human Nature had argued that we only know the mind through a subjective—essentially illusory—series of perceptions. Ideas such as causality, morality, and objects are not evident in experience, so their reality may be questioned. Kant felt that reason could remove this skepticism, and he set himself to solving these problems. Although fond of company and conversation with others, Kant isolated himself, and resisted friends' attempts to bring him out of his isolation. When Kant emerged from his silence in 1781, the result was the Critique of Pure Reason. Kant countered Hume's empiricism by claiming that some knowledge exists inherently in the mind, independent of experience. He drew a parallel to the Copernican revolution in his proposal that worldly objects can be intuited a priori ('beforehand'), and that intuition is consequently distinct from objective reality. He acquiesced to Hume somewhat by defining causality as a "regular, constant sequence of events in time, and nothing more."
Although now uniformly recognized as one of the greatest works in the history of philosophy, this Critique was largely ignored upon its initial publication. The book was long, over 800 pages in the original German edition, and written in a convoluted style. It received few reviews, and these granted it no significance. Kant's former student, Johann Gottfried Herder criticized it for placing reason as an entity worthy of criticism instead of considering the process of reasoning within the context of language and one's entire personality. Similar to Christian Garve and Johann Georg Heinrich Feder, he rejected Kant's position that space and time possessed a form that could be analyzed. Additionally, Garve and Feder also faulted Kant's Critique for not explaining differences in perception of sensations. Its density made it, as Herder said in a letter to Johann Georg Hamann, a "tough nut to crack", obscured by "all this heavy gossamer". Its reception stood in stark contrast to the praise Kant had received for earlier works, such as his Prize Essay and shorter works that preceded the first Critique. These well-received and readable tracts include one on the earthquake in Lisbon that was so popular that it was sold by the page. Prior to the change in course documented in the first Critique, his books had sold well. Kant was disappointed with the first Critique's reception. Recognizing the need to clarify the original treatise, Kant wrote the Prolegomena to any Future Metaphysics in 1783 as a summary of its main views. Shortly thereafter, Kant's friend Johann Friedrich Schultz (1739–1805) (professor of mathematics) published Erläuterungen über des Herrn Professor Kant Critik der reinen Vernunft (Königsberg, 1784), which was a brief but very accurate commentary on Kant's Critique of Pure Reason.
Kant's reputation gradually rose through the latter portion of the 1780s, sparked by a series of important works: the 1784 essay, "Answer to the Question: What is Enlightenment?"; 1785's Groundwork of the Metaphysics of Morals (his first work on moral philosophy); and, from 1786, Metaphysical Foundations of Natural Science. But Kant's fame ultimately arrived from an unexpected source. In 1786, Karl Leonhard Reinhold published a series of public letters on Kantian philosophy. In these letters, Reinhold framed Kant's philosophy as a response to the central intellec
Immanuel Kant