The history of Immanuel Kant’s life is difficult to portray, for he had neither life nor history. He led a mechanically ordered, almost abstract bachelor existence in a quiet, remote little street in Koenigsberg, an old town on the northeastern border of Germany. I do not believe that the great clock of the cathedral there performed more dispassionately and methodically its outward routine of the day than did its fellow countryman Immanuel Kant. Getting up in the morning, drinking coffee, writing, giving lectures, eating, walking, everything had its appointed time, and the neighbors knew for certain that it was half-past three when Immanuel Kant, in his gray frock-coat, his Spanish cane in his hand, stepped out of his house and strolled to the little linden avenue called after him to this day the “Philosopher’s Path.” Eight times he walked up and down it, in every season of the year, and when the sky was overcast, or gray clouds announced a rain coming, old Lampe, his servant, was seen walking anxiously behind him with a big umbrella under his arm, like an image of providence.
What a strange contrast between the outward life of the man and his destructive, world-crushing thoughts! Truly, if the citizens of Koenigsberg had had any premonition of the full significance of his ideas, they would have felt a far more terrifying dread at the presence of this man than at the sight of an executioner, an executioner who merely executes people. But the good folk saw in him nothing but a professor of philosophy, and as he passed by at his customary hour, they gave him a friendly greeting and perhaps set their watches by him.
If, however, Immanuel Kant, the arch-destroyer in the realm of ideas, far surpassed Maximilian Robespierre in terrorism, yet he possessed many similarities with the latter which invite comparison of the two men. In the first place, we find in both the same stubborn, keen, unpoetic, sober integrity. We also find in both the same talent for suspicion, only that the one directs his suspicion toward ideas and calls it criticism, while the other applies it to people and entitles it republican virtue. But both represented in the highest degree the type of provincial bourgeois. Nature had destined them to weigh coffee and sugar, but Fate determined that they should weigh other things and placed on the scales of the one a king, on the scales of the other a god.
And they gave the correct weight!~ Heinrich Heine in On the History of Religion and Philosophy in Germany (1835)