We find that the more a cultivated reason devotes itself to the aim of enjoying life and happiness, the further does man get away from true contentment.
It is presumed that there exists a great unity in nature, in respect of the adequacy of a single cause to account for many different kinds of consequences.
Often war is waged only in order to show valor; thus an inner dignity is ascribed to war itself, and even some philosophers have praised it as an ennoblement of humanity, forgetting the pronouncement of the Greek who said, 'War is an evil in as much as it produces more wicked men than it takes away.'
The ultimate destiny of the human race is the greatest moral perfection, provided that it is achieved through human freedom, whereby alone man is capable of the greatest happiness.
There is needed, no doubt, a body of servants (ministerium) of the invisible church, but not officials (officiales), in other words, teachers but not dignitaries, because in the rational religion of every individual there does not yet exist a church as a universal union (omnitudo collectiva).
A science of all these possible kinds of space [the higher dimensional ones] would undoubtedly be the highest enterprise which a finite understanding could undertake in the field of geometry... If it is possible that there could be regions with other dimensions, it is very likely that God has somewhere brought them into being.
Aristotle can be regarded as the father of logic. But his logic is too scholastic, full of subtleties, and fundamentally has not been of much value to the human understanding. It is a dialectic and an organon for the art of disputation.
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.