“In every civilization, however generally prosaic, however addicted to the short-time point of view on human affairs, there are always certain alien spirits who, while outwardly conforming to the requirements of the civilization around them, still keep a disinterested regard for the plain intelligible law of things, irrespective of any practical end.”

On Italians, sometimes cited to The Rommel Papers (1953) edited by Basil Henry Liddell Hart, but without specific chapter or page citations; it seems to summarize an attitude indicated by Rommel in Ch. 11 of that work, but no published occurrence of this has actually been located.
Disputed

This Business of Living (1935-1950)

Source: Passionate Declarations: Essays on War and Justice

Ideology and Utopia (1929)

Source: Seven Great Statesmen in the Warfare of Humanity with Unreason (1915), p. 55-56
Context: Into the very midst of all this welter of evil, at a point in time to all appearance hopeless, at a point in space apparently defenseless, in a nation of which every man, woman, and child was under sentence of death from its sovereign, was born a man who wrought as no other has ever done for a redemption of civilization from the main cause of all that misery; who thought out for Europe the precepts of right reason in international law; who made them heard; who gave a noble change to the course of human affairs; whose thoughts, reasonings, suggestions, and appeals produced an environment in which came an evolution of humanity that still continues. Huig de Groot, afterward known to the world as Hugo Grotius was born at Delft in Holland on Easter day of 1583. It was at the crisis of the struggle between Spain and the Netherlands. That struggle had already continued for twenty years, and just after the close of his first year, in the very town where he was lying in his cradle, came its most fearful event, that which maddened both sides—the assassination of William of Orange, nominally by Balthazar Gerard, really by Philip II of Spain.

The Autobiography of Will Rogers (1949)
Variant: You can't say that civilization don't advance, however, for in every war they kill you in a new way.

Source: General System Theory (1968), 2. The Meaning of General Systems Theory, p. 37

Source: Social Problems (1883), Ch. 21 : Conclusion
Context: The progress of civilization necessitates the giving of greater and greater attention and intelligence to public affairs. And for this reason I am convinced that we make a great mistake in depriving one sex of voice in public matters, and that we could in no way so increase the attention, the intelligence and the devotion which may be brought to the solution of social problems as by enfranchising our women.

During his scholarly lecture tours as a philosopher, in Ghana, in Jayachamaraja Wodeyar – A Princely scholar http://www.mysoresamachar.com/j_wadiyar_ann2.htm