Now the maximum of perfection is called ideal, by Plato, Idea — for instance, his Idea of a Republic — and is the principle of all that is contained … - Immanuel Kant

...[T]here is no art in being intelligible if one renounces all thoroughness of insight; but also it produces a disgusting medley of compiled observations and half-reasoned principles. Shallow pates enjoy this because it can be used for everyday chat, but the sagacious find in it only confusion, and being unsatisfied and unable to help themselves, they turn away their eyes, while philosophers, who see quite well through this delusion, are little listened to when they call men off for a time from this pretended popularity in order that they might be rightfully popular after they have attained a definite insight.

If we were to suppose that mankind never can or will be in a better condition, it seems impossible to justify by any kind of theodicy the mere fact that such a race of corrupt beings could have been created on earth at all.

...Reason should take on anew the most difficult of all its tasks, namely, that of self-knowledge, and to institute a court of justice, by which reason may secure its rightful claims while dismissing all its groundless pretensions, and this not by mere decrees but according to its own eternal and unchangeable laws; and this court is none other than the critique of pure reason itself.