“The price of empire is America's soul, and that price is too high.”

The Cost of a Laugh, Motion Picture Magazine, March 1918. http://archive.org/stream/motionpicturemag152moti#page/n75/mode/2up

Book Two, Part I “Yellow City”, Chapter 5 (p. 152)
Vazkor, Son of Vazkor (1978)

Source: The Art of War, Chapter II · Waging War

Retirement ceremony, Friday, 23 July 2010, as quoted in The New York Times http://www.nytimes.com/2010/07/24/us/24mcchrystal.html.
2010
Context: Service in this business is tough and often dangerous. It extracts a price for participants, and that price can be high. It is tempting to protect yourself from the personal and professional cost of loss by limiting how much you commit, how much you believe and trust in people, and how deeply you care… If I had it to do over again, I’ d do some things in my career differently, but not many. I believed in people and I still believe in them. I trusted and I still trust. I cared and I still care. I wouldn’ t have had it any other way.

Source: The 48 Laws of Power

On the Death of Mr. Addison (1721), line 81. Compare: "He who should teach men to die, would at the same time teach them to live", Michel de Montaigne, Essay, book i. chap. ix.; "I have taught you, my dear flock, for above thirty years how to live; and I will show you in a very short time how to die", Sandys, Anglorum Speculum, p. 903; "Teach him how to live, And, oh still harder lesson! how to die", Beilby Porteus, Death, line 316; "He taught them how to live and how to die", Somerville, In Memory of the Rev. Mr. Moore.
Context: There patient show'd us the wise course to steer,
A candid censor, and a friend severe;
There taught us how to live; and (oh! too high
The price for knowledge) taught us how to die.

2000s, Where the Right Went Wrong (2004)

Des Moines Iowa speech (1 February 1916) http://www.combat.ws/S3/BAKISSUE/CMBT01N2/SMOKE.HTM, on "The Westerm Preparedness Tour" http://www.allthingswilliam.com/presidents/wilson.html
1910s