Enlightenment is man's leaving his self-caused immaturity. Immaturity is the incapacity to use one's intelligence without the guidance of another. Such immaturity is self-caused if it is not caused by lack of intelligence, but by lack of determination and courage to use one's intelligence without being guided by another. Sapere Aude! Have the courage to use your own intelligence! is therefore the motto of the enlightenment.
Laziness and cowardice explain why so many men. . . remain under a life-long tutelage and why it is so easy for some men to set themselves up as the guardians of all the rest. . . If I have a book which understands for me, a pastor who has a conscience for me, a doctor who decides my diet, I need not trouble myself. If I am willing to pay, I need not think. Others will do it for me.
Reason in a creature is a faculty of widening the rules and purposes of the use of all its powers far beyond natural instinct; it acknowledges no limits to its projects. Reason itself does not work instinctively, but requires trial, practice, and instruction in order gradually to progress from one level of insight to another.
Two things fill the mind with ever new and increasing admiration and awe, the oftener and more steadily we reflect on them: the starry heavens above me and the moral law within me.
Our knowledge springs from two fundamental sources of the mind; the first is the capacity of receiving representations (receptivity for impressions), the second is the power of knowing an object through these representations (spontaneity [in the production] of concepts).
cruelty to animals is contrary to man's duty to himself, because it deadens in him the feeling of sympathy for their sufferings, and thus a natural tendency that is very useful to morality in relation to other human beings is weakened.
The arts of speech are rhetoric and poetry. Rhetoric is the art of transacting a serious business of the understanding as if it were a free play of the imagination; poetry that of conducting a free play of the imagination as if it were a serious business of the understanding.
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.
Enlightenment is the liberation of man from his self-caused state of minority... Supere aude! Dare to use your own understanding!is thus the motto of the Enlightenment.