Deaths, births, and marriages, considering how much they are separately dependent on the freedom of the human will, should seem to be subject to no law according to which any calculation could be made beforehand of their amount; and yet the yearly registers of these events in great countries prove that they go on with as much conformity to the laws of nature as the oscillations of the weather.
The sceptics, a kind of nomads, despising all settled culture of the land, broke up from time to time all civil society. Fortunately their number was small, and they could not prevent the old settlers from returning to cultivate the ground afresh, though without any fixed plan or agreement.
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.
Things which we see are not by themselves what we see ... It remains completely unknown to us what the objects may be by themselves and apart from the receptivity of our senses. We know nothing but our manner of perceiving them.
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.
Upon the solution of this problem, or upon sufficient proof of the impossibility of synthetical knowledge a priori, depends the existence or downfall of metaphysics.
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... Morality is not properly the doctrine of how we may make ourselves happy, but how we may make ourselves worthy of happiness.
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.
At some future day it will be proved, I cannot say when and where, that the human soul is, while in earth life, already in an uninterrupted communication with those living in another world.
We come no nearer the infinitude of the creative power of God, if we enclose the space of its revelation within a sphere described with the radius of the Milky Way, than if we were to limit it to a ball an inch in diameter. All that is finite, whatever has limits and a definite relation to unity, is equally far removed from the infinite... Eternity is not sufficient to embrace the manifestations of the Supreme Being, if it is not combined with the infinitude of space.
No state at war with another state should engage in hostilities of such a kind as to render mutual confidence impossible when peace will have been made.
Marriage...is the union of two people of different sexes with a view to the mutual possession of each other's sexual attributes for the duration of their lives.
All thought must, directly or indirectly, by way of certain characters, relate ultimately to intuitions, and therefore, with us, to sensibility, because in no other way can an object be given to us.