But under a constitution where the subject is not a citizen, and which is therefore not republican, it is the simplest thing in the world to go to wa… - Immanuel Kant

Under a nonrepublican constitution, where subjects are not citizens, the easiest thing in the world to do is to declare war. Here the ruler is not a fellow citizen, but the nation's owner, and war does not affect his table, his hunt, his places of pleasure, his court festivals, and so on. Thus, he can decide to go to war for the most meaningless of reasons, as if it were a kind of pleasure party...

It falls into this difficulty without any fault of its own. It begins with principles, which cannot be dispensed with in the field of experience, and the truth and sufficiency of which are, at the same time, insured by experience. With these principles it rises, in obedience to the laws of its own nature, to ever higher and more remote conditions. But it quickly discovers that, in this way, its labours must remain ever incomplete, because new questions never cease to present themselves; and thus it finds itself compelled to have recourse to principles which transcend the region of experience, while they are regarded by common sense without distrust. It thus falls into confusion and contradictions, from which it conjectures the presence of latent errors, which, however, it is unable to discover, because the principles it employs, transcending the limits of experience, cannot be tested by that criterion. The arena of these endless contests is called Metaphysic.

That religion in which I must know in advance that something is a divine command in order to recognize it as my duty, is the revealed religion (or the one standing in need of a revelation); in contrast, that religion in which I must first know that something is my duty before I can accept it as a divine injunction is the natural religion. … When religion is classified not with reference to its first origin and its inner possibility (here it is divided into natural and revealed religion) but with respect to its characteristics which make it capable of being shared widely with others, it can be of two kinds: either the natural religion, of which (once it has arisen) everyone can be convinced through his own reason, or a learned religion, of which one can convince others only through the agency of learning (in and through which they must be guided). … A religion, accordingly, can be natural, and at the same time revealed, when it is so constituted that men could and ought to have discovered it of themselves merely through the use of their reason, although they would not have come upon it so early, or over so wide an area, as is required. Hence a revelation thereof at a given time and in a given place might well be wise and very advantageous to the human race, in that, when once the religion thus introduced is here, and has been made known publicly, everyone can henceforth by himself and with his own reason convince himself of its truth. In this event the religion is objectively a natural religion, though subjectively one that has been revealed.

Agisci in modo da considerare l’umanità come scopo, e mai come semplice mezzo.