The ideal of the supreme being is nothing but a regulative principle of reason which directs us to look upon all connection in the world as if it originated from an all-sufficient necessary cause.
If it were possible for us to have so deep an insight into a man's character as shown both in inner and in outer actions, that every, even the least, incentive to these actions and all external occasions which affect them were so known to us that his future conduct could be predicted with as great a certainty as the occurrence of a solar or lunar eclipse, we could nevertheless still assert that the man is free.
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).
Most men use their knowledge only under guidance from others because they lack the courage to think independently using their own reasoning abilities. It takes intellectual daring to discover the truth.
That Logic has advanced in this sure course, even from the earliest times, is apparent from the fact that, since Aristotle, it has been unable to advance a step, and thus to all appearance has reached its completion.
Moral Teleology supplies the deficiency in physical Teleology , and first establishes a Theology ; because the latter, if it did not borrow from the former without being observed, but were to proceed consistently, could only found a Demonology , which is incapable of any definite concept.
Reason must approach nature in order to be taught by it. It must not, however, do so in the character of a pupil who listens to everything that the teacher chooses to say, but of an appointed judge who compels the witness to answer questions which he has himself formulated.
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.