I feel a complete thirst for knowledge and an eager unrest to go further in it as well as satisfaction at every acquisition. There was a time when I believed that this alone could constitute the honor of mankind, and I had contempt for the ignorant rabble who know nothing.
Perhaps a revolution can overthrow autocratic despotism and profiteering or power-grabbing oppression, but it can never truly reform a manner of thinking; instead, new prejudices, just like the old ones they replace, will serve as a leash for the great unthinking mass.
This can never become popular, and, indeed, has no occasion to be so; for fine-spun arguments in favour of useful truths make just as little impression on the public mind as the equally subtle objections brought against these truths. On the other hand, since both inevitably force themselves on every man who rises to the height of speculation, it becomes the manifest duty of the schools to enter upon a thorough investigation of the rights of speculative reason, and thus to prevent the scandal which metaphysical controversies are sure, sooner or later, to cause even to the masses.
Natural science physics contains in itself synthetical judgments a priori, as principles. ... Space then is a necessary representation a priori, which serves for the foundation of all external intuitions.
Beneficence is a duty; and he who frequently practices it, and sees his benevolent intentions realized comes, at length, really to love him to whom he has done good.
We assume a common sense as the necessary condition of the universal communicability of our knowledge, which is presupposed in every logic and every principle of knowledge that is not one of skepticism.
Philosophical knowledge is the knowledge gained by reason from concepts ; mathematical knowledge is the knowledge gained by reason from the construction of concepts.