“We are to work after no set fashion of high endeavor; but to walk with Jesus, performing, as it were, a ministry on foot, that we may stop at the humblest matter, and prove our fidelity there.”

"The Heart of Noon", p. 116
Desert Solitaire (1968)

From an alleged Letter of to his Minister of the Interior on the Poor Laws. Pub. in The Press, Feb. 1, 1868.
Attributed

"A Pledge of Allegiance" - speech for "I Am an Amercan Day" Central Park, New York, New York. (20 May 1945) Hand credited H. G. Wells with inspiring some of the ideas expressed in this speech.
Extra-judicial writings
Context: We may not stop until we have done our part to fashion a world in which there shall be some share of fellowship; which shall be better than a den of thieves. Let us not disguise the difficulties; and, above all, let us not content ourselves with nobel aspirations, counsels of perfection, and self-righteous advice to others. We shall need the wisdom of the serpent; we shall have to be content with short steps; we shall be obliged to give and take; we shall face the strongest passions of mankind — our own not the least; and in the end we shall have fabricated an imperfect instrument. But we shall not wholly have failed; we shall have gone forward, if we bring to our task a pure and chastened spirit, patience, understanding, sympathy, forbearance, generosity, fortitude, and, above all, an inflexible determination. The history of man has just begun; in the aeons which lie before him lie limitless hope or limitless despair. The choice is his; the present choice is ours. It is worth the trial.

Letter 2
Letters on Logic: Especially Democratic-Proletarian Logic (1906)

Many attribute this quote to Marshall, however, General Omar Bradley is the correct author. Statement by Bradley (31 May 1948), quoted in An Inconvenient Truth : The Planetary Emergency Of Global Warming And What We Can Do About It (2006) by Al Gore.
Misattributed

John The Beloved Disciple In His Old Age: On Jesus The Word
Jesus, The Son of Man (1928)
Context: We are all sons and daughters of the Most High, but the Anointed One was His first-born, who dwelt in the body of Jesus of Nazareth, and He walked among us and we beheld Him.
All this I say that you may understand not only in the mind but rather in the spirit. The mind weighs and measures but it is the spirit that reaches the heart of life and embraces the secret; and the seed of the spirit is deathless.
The wind may blow and then cease, and the sea shall swell and then weary, but the heart of life is a sphere quiet and serene, and the star that shines therein is fixed for evermore.

This is a misquotation of a prayer from the 1928 Book of Common Prayer (ministry should be industry and arrogance should be arrogancy). This was a revision from an earlier edition. The original form, written by George Lyman Locke, appeared in the 1885 edition. In 1994 William J. Federer attributed it to Jefferson in America's God and Country: Encyclopedia of Quotations, pp. 327-8. See the Thomas Jefferson Encyclopedia http://www.monticello.org/site/research-and-collections/national-prayer-peace.
Misattributed

"An International Administrative Service", From an Address to the International Law Association at McGill University, Montreal, 30 May, 1956. Wilder Foote (Ed.), The Servant of Peace, A Selection of the Speeches and Statements of Dag Hammarskjöld, The Bodley Head, London 1962, p. 116.
Context: Do we refer to the purposes of the Charter? They are expressions of universally shared ideals which cannot fail us, though we, alas, often fail them. Or do we think of the institutions of the United Nations? They are our tools. We fashioned them. We use them. It is our responsibility to remedy any flaws there may be in them.... This is a difficult lesson for both idealists and realists, though for different reasons. I suppose that, just as the first temptation of the realist is the illusion of cynicism, so the first temptation of the idealist is the illusion of Utopia.

Source: Interior Castle