It is precisely in knowing its limits that philosophy consists. - 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...

What vexations there are in the external customs which are thought to belong to religion, but which in reality are related to ecclesiastical form! The merits of piety have been set up in such away that the ritual is of no use at all except for the simple submission of the believers to ceremonies and observances, expiations and mortifications (the more the better). But such compulsory services, which are mechanically easy (because no vicious inclination is thus sacrificed), must be found morally very difficult and burdensome to the rational man. When, therefore, the great moral teacher said, 'My commandments are not difficult,' he did not mean that they require only limited exercise of strength in order to be fulfilled. As a matter of fact, as commandments which require pure dispositions of the heart, they are the hardest that can be given. Yet, for a rational man, they are nevertheless infinitely easier to keep than the commandments involving activity which accomplishes nothing... [since] the mechanically easy feels like lifting hundredweights to the rational man when he sees that all the energy spent is wasted.

Enlightenment is man's emergence from his self-imposed immaturity. Nothing is required for this enlightenment except freedom; and the freedom in question is the least harmful of all, namely, the freedom to use with and publicly in all matters.