“Skepticism is thus a resting-place for human reason, where it can reflect upon its dogmatic wanderings and make survey of the region in which it finds itself, so that for the future it may be able to choose its path with more certainty. But it is no dwelling-place for permanent settlement. Such can be obtained only through perfect certainty in our knowledge, alike of the objects themselves and of the limits within which all our knowledge of objects is enclosed.”

“One age cannot bind itself, and thus conspire, to place a succeeding one in a condition whereby it would be impossible for the later age to expand its knowledge (particularly where it is so very important), to rid itself of errors, and generally to increase its enlightenment. That would be a crime against human nature, whose essential destiny lies precisely in such progress; subsequent generations are thus completely justified in dismissing such agreements as unauthorized and criminal. The criterion of everything that can be agreed upon as a law by a people lies in this question: Can a people impose such a law on itself?”

“All rational knowledge is either material, and concerns some objects, or formal, and is occupied only with the form of understanding and reason itself and with the universal rules of thinking, without regard to distinctions among objects. formal philosophy is called logic. Material philosophy, however, which has to do with definite object objects and the laws to which they are subject, is divided into two parts. This is because these laws are either laws of nature or laws of freedom. The science of the former is called physics, and that of the latter ethics. The former is also called theory of nature and the latter theory of morals.”

“All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason.”

“A categorical imperative would be one which represented an action as objectively necessary in itself, without reference to any other purpose.”

“An age cannot bind itself and ordain to put the succeeding one into such a condition that it cannot extend its (at best very occasional) knowledge , purify itself of errors, and progress in general enlightenment. That would be a crime against human nature, the proper destination of which lies precisely in this progress and the descendants would be fully justified in rejecting those decrees as having been made in an unwarranted and malicious manner.The touchstone of everything that can be concluded as a law for a people lies in the question whether the people could have imposed such a law on itself.”

“The first impression of the writings of Mr. J. J. Rousseau received by a knowledgeable reader, who is reading for something more than vanity or to kill time, is that he is encountering a lucidity of mind, a noble impulse of genius and a sensitive soul of such a high level that perhaps never an author of whatever epoch or of whatever people has been able to possess in combination. The impression that immediately follows is bewilderment over the strange and contradictory opinions, which so oppose those which are in general circulation that one can easily come to the suspicion that the author, by virtue of his extraordinary talent, wishes to show off only the force of his bewitching wit and through the magic of rhetoric make himself something apart who through captivating novelties stands out among all rivals at wit.”