“There is no ideal system just as there are no ideal persons, ideal families or ideal cities, we have to get away from ideals.”

As quoted in "The Watchman" in TIME magazine (16 August 1948) http://www.time.com/time/magazine/article/0,9171,798932-2,00.html

House & Garden (July 1991), p. 120.

2014, Address to European Youth (March 2014)
Context: None of us can know for certain what the coming days will bring in Ukraine, but I am confident that eventually those voices -- those voices for human dignity and opportunity and individual rights and rule of law -- those voices ultimately will triumph. I believe that over the long haul, as nations that are free, as free people, the future is ours. I believe this not because I’m naïve, and I believe this not because of the strength of our arms or the size of our economies, I believe this because these ideals that we affirm are true; these ideals are universal.

"December 11 : Wind", p. 152
A Year in the Maine Woods (1995)

1920s, Speech on the Anniversary of the Declaration of Independence (1926)
Context: Governments do not make ideals, but ideals make governments. This is both historically and logically true. Of course the government can help to sustain ideals and can create institutions through which they can be the better observed, but their source by their very nature is in the people. The people have to bear their own responsibilities. There is no method by which that burden can be shifted to the government. It is not the enactment, but the observance of laws, that creates the character of a nation.

As quoted by Rolf Edberg, Swedish Ambassador to Norway, accepting the Nobel Peace Prize on behalf of Hammarskjöld in Oslo, Norway (10 December 1961) http://nobelprize.org/nobel_prizes/peace/laureates/1961/hammarskjold-acceptance.html

No known source; it appears to be a paraphrase of the last sentence of Einstein's "An Ideal of Service to Our Fellow Man". Earliest known attribution is in the Washingon Afro-American, AFRO Magazine Section, Sept 21, 1954, p. 2 http://news.google.com/newspapers?id=I8slAAAAIBAJ&sjid=6_QFAAAAIBAJ&pg=4494,1273325
Disputed

Variant translations:
Blessed is he who carries within himself a God, an ideal, and who obeys it: ideal of art, ideal of science, ideal of the gospel virtues, therein lie the springs of great thoughts and great actions; they all reflect light from the Infinite. (As quoted by Sir William Osler in his introduction to The Life of Pasteur (1907) by Rene Vallery-Radot, as translated by R .L. Devonshire (1923)
Blessed is he who carries within himself a god and an ideal and who obeys it — an ideal of art, of science, or gospel virtues. Therein lie the springs of great thoughts and great actions; they all reflect light from the Infinite. (As quoted in The Wordsworth Dictionary of Quotations (1998) by Connie Robertson, p. 320)
Discours de réception de Louis Pasteur (1882)
Original: (fr) La grandeur des actions humaines se mesure à l’inspiration qui les fait naître. Heureux celui qui porte en soi un Dieu, un idéal de la beauté et qui lui obéit : idéal de l’art, idéal de la science, idéal de la patrie, idéal des vertus de l’Évangile! Ce sont là les sources vives des grandes pensées et des grandes actions. Toutes s’éclairent des reflets de l’infini.

The Lawless Roads (1939)