From Schiller's letters on aesthetics

"But we know that the condition of the human will always remains contingent, and that only in the Absolute Being physical coexists with moral necessity. Accordingly, if it is wished to depend on the moral conduct of man as on natural results, this conduct must become nature, and he must be led by natural impulse to such a course of action as can only and invariably have moral results. But the will of man is perfectly free between inclination and duty, and no physical necessity ought to enter as a sharer in this magisterial personality. If, therefore, he is to retain this power of solution, and yet become a reliable link in the causal concatenation of forces, this can only be effected when the operations of both these impulses are presented quite equally in the world of appearances. It is only possible when, with every difference of form, the matter of man's volition remains the same, when all his impulses agreeing with his reason are sufficient to have the value of a universal legislation."

From Schiller's letters on aesthetics

"The great point is, therefore, to reconcile these two considerations, to prevent physical society from ceasing for a moment in time, while the moral society is being formed in the idea; in other words, to prevent its existence from being placed in jeopardy for the sake of the moral dignity of man. When the mechanic has to mend a watch he lets the wheels run out; but the living watchworks of the state have to be repaired while they act, and a wheel has to be exchanged for another during its revolutions. Accordingly props must be sought for to support society and keep it going while it is made independent of the natural condition from which it is sought to emancipate it.

"This prop is not found in the natural character of man, who, being selfish and violent, directs his energies rather to the destruction than to the preservation of society. Nor is it found in his moral character, which has to be formed, which can never be worked upon or calculated on by the lawgiver, because it is free and never appears. It would seem, therefore, that another measure must be adopted. It would seem that the material character of the arbitrary must be separated from moral freedom; that it is incumbent to make the former harmonize with the laws and the latter dependent on impressions; it would be expedient to remove the former still farther from matter and to bring the latter somewhat more near to it; in short, to produce a third character related to both the others—the material and the moral—paving the way to a transition from the sway of mere force to that of law, without preventing the proper development of the moral character, but serving rather as a pledge in the sensuous sphere of a morality in the unseen.

[...] Art, like science, is emancipated from all that is positive, and all that is humanly conventional; both are completely independent of the arbitrary will of man. The political legislator may place their empire under an interdict, but he cannot reign there. He can proscribe the friend of truth, but truth subsists; he can degrade the artist, but he cannot change art. No doubt, nothing is more common than to see science and art bend before the spirit of the age, and creative taste receive its law from critical taste. When the character becomes stiff and hardens itself, we see science severely keeping her limits, and art subject to the harsh restraint of rules; when the character is relaxed and softened, science endeavors to please and art to rejoice. For whole ages philosophers as well as artists show themselves occupied in letting down truth and beauty to the depths of vulgar humanity. They themselves are swallowed up in it; but, thanks to their essential vigor and indestructible life, the true and the beautiful make a victorious fight, and issue triumphant from the abyss."