"Give me matter, and I will construct a world out of it!"

"Morality is not the doctrine of how we may make ourselves happy, but how we may make ourselves worthy of happiness."

"But only he who, himself enlightened, is not afraid of shadows."

"Two things fill the mind with ever new and increasing admiration and awe, the more often and steadily we reflect upon them: the starry heavens above me and the moral law within me. I do not seek or conjecture either of them as if they were veiled obscurities or extravagances beyond the horizon of my vision; I see them before me and connect them immediately with the consciousness of my existence."

"All the interests of my reason, speculative as well as practical, combine in the three following questions: 1. What can I know? 2. What ought I to do? 3. What may I hope?"

"Religion is the recognition of all our duties as divine commands."

"It is beyond a doubt that all our knowledge that begins with experience."

"From such crooked wood as that which man is made of, nothing straight can be fashioned."

"Everything in nature acts in conformity with law."

"It is not God's will merely that we should be happy, but that we should make ourselves happy."

"If adversity and hopeless grief have quite taken away the taste for life; if an unfortunate man, strong of soul and more indignant about his fate than despondent or dejected, wishes for death and yet preserves his life without loving it, not from inclination or fear but from duty, then his maxim has moral content."

"Every man is to be respected as an absolute end in himself: and it is a crime against the dignity that belongs to him as a human being to use him as a mere means for some external purpose."

"But, though all our knowledge begins with experience, it by no means follows that all arises out of experience."

"Only the descent into the hell of self-knowledge can pave the way to godliness."

"Reason of itself, independent on all experience, ordains what ought to take place, that accordingly actions of which perhaps the world has hitherto never given an example, the feasibility even if which might be very much doubted by one who founds everything on experience, are nevertheless inflexibly commanded by reason; that, for example, even though there might never yet have been a sincere friend, yet not a whit the less is pure sincerity in friendship required of every man."

"Would it not therefore be wiser in moral concerns to acquiesce in the judgement of common reason, or at most only to call in philosophy for the purpose of rendering the system of morals more complete and intelligible, and its rules more convenient for use (especially for disputation), but not so as to draw off the common understanding from its happy simplicity, or to bring it by means of philosophy into a new path of inquiry and instruction?"

"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.."

"Thoughts without content are empty, intuitions without concepts are blind."

"The enjoyment of power inevitably corrupts the judgement of reason, and perverts its liberty."

"El sabio puede cambiar de opinion. El necio, nunca."

"Happiness is not an ideal of reason, but of imagination."

"(On the seeming futility of metaphysics) Why then has nature afflicted our reason with the restless striving for such a path, as if it were one of reason's most important occupations? Still more, how little cause have we to place trust in our reason if in one of the most important parts of our desire for knowledge it does not merely forsake us but even entices us with delusions and in the end betrays us! Or if the path has merely eluded us so far, what indications may we use that might lead us to hope that in renewed attempts we will be luckier than those who have gone before us?"

"To know what questions may reasonably be asked is already a great and necessary proof of sagacity and insight. For if a question is absurd in itself and calls for unnecessary answers, it not only brings disgrace to the person raising it, but may prompt an incautious listener to give absurd answers, thus presenting, as the ancients said, the laughable spectacle of one person milking a he-goat, and another holding the sieve underneath."

"Freedomis a property of all rational beings."

"Genius is the ability to independently arrive at and understand concepts that would normally have to be taught by another person."

"Two things awe me most, the starry sky above me and the moral law within me."

"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."

"Enlightenment is man's release from his self-incurred tutelage. Tutelage is man's inability to make use of his understanding without direction from another. Self-incurred is this tutelage when its cause lies not in lack of reason but in lack of resolution and courage to use it without direction from another. Sapere aude! 'Have courage to use your own reason!'- that is the motto of enlightenment."

"A good will is good not because of what it performs or effects, not by its aptness for the attainment of some proposed end, but simply by virtue of the volition - that is, it is good in itself, and considered by itself is to be esteemed much higher than all that can be brought about by it in favor of any inclination, nay, even of the sum-total of all inclinations... like a jewel, it would still shine by its own light, as a thing which has its whole value in itself."

"Settle, for sure and universally, what conduct will promote the happiness of a rational being."

"Experience without theory is blind, but theory without experience is mere intellectual play."

"Since in early youth it cannot be known what ends are likely to occur to us in the course of life, parents seek to have their children taught a great many things, and provide for their skill in the use of means for all sorts of arbitrary ends, of none of which can they determine whether it may not perhaps hereafter be an object to determine their pupil, but which it is at all events possible that he might aim at; and this anxiety is so great that they commonly neglect to form and correct their judgement on the value of the things which may be chosen as ends."

"Act only according to that maxim whereby you can at the same time will that it should become a universal law."

"It is nevertheless better than the theological concept, of deriving morality from a divine, all-perfect will, not merely because we do not intuit this perfection, but can derive it solely from our concepts, of which morality is the foremost one, but because if we do not do this (which, if we did, would be a crude circle in explanation), the concept of his will that is left over to us, the attributes of the desire for glory and domination, bound up with frightful representations of power and vengeance, would have to make a foundation for a system of morals that is directly opposed to morality."

"To be is to do."

"True politics cannot take a single step without first paying homage to morals, and while politics itself is a difficult art, its combination with morals is no art at all; for morals cuts the Gordian knot which politics cannot solve as soon as the two are in conflict."

"The schematicism by which our understanding deals with the phenomenal world ... is a skill so deeply hidden in the human soul that we shall hardly guess the secret trick that Nature here employs."

"Two things fill the mind with ever-increasing wonder and awe, the more often and the more intensely the mind of thought is drawn to them: the starry heavens above me and the moral law within me."

"Enlightenment is man's emergence from his self-imposed immaturity. Nothing is required for this enlightenment except freedom; and the freedom in question is the least harmful of all, namely, the freedom to use with and publicly in all matters."

"I am never to act otherwise than so that I could also will that my maxim should become universal law."

"The will is conceived as a faculty of determining oneself to action in accordance with the conception of certain laws. And such a faculty can be found only in rational beings."

"I class the principle of moral feeling under that of happiness, because every empirical interest promises to contribute to our well-being by the agreeableness that a thing affords, whether profit be regarded."

"If man makes himself a worm he must not complain when he is trodden on."

"Act that your principle of action might safely be made a law for the whole world."

"Human beings are never to be treated as a means but always as ends."

"To behold virtue in her proper form is nothing else but to contemplate morality stripped of all admixture of sensible things and of every spurious ornament of reward or self-love. How much she then eclipses everything else that appears charming to the affections, every one may readily perceive with the least exertion of his reason, if it be not wholly spoiled for abstraction."

"What can I know? What ought I to do? What can I hope?"

"Thus he has two standpoints from which he can consider himself...: first, as belonging to the world of sense, under the laws of nature (heteronomy), and, second, as belonging to the intelligible world under laws which, independent of nature, are not empirical but founded only on reason."

"In every department of physical science there is only so much science, properly so-called, as there is mathematics."

"The death of dogma is the birth of morality."