“Courage, ne'er by sorrow broken!
Aid where tears of virtue flow;
Faith to keep each promise spoken!
Truth alike to friend and foe!”

Speech at Arlington Cemetery, Decoration Day (30 May 1868)
1860s
Context: I am oppressed with a sense of the impropriety of uttering words on this occasion. If silence is ever golden, it must be here, beside the graves of fifteen thousand men, whose lives were more significant than speech, and whose death was a poem, the music of which can never be sung. With words we make promises, plight faith, praise virtue. Promises may not be kept, plighted faith may be broken, and vaunted virtue be only the cunning mask of vice. We do not know one promise these men made, one pledge they gave, one word they spoke: but we do know they summed up and perfected, by one supreme act, the highest virtues of men and citizens. For love of country they accepted death, and thus resolved all doubts, and made immortal their patriotism and their virtue.

born in this century, tempered by war, disciplined by a hard and bitter peace, proud of our ancient heritage — and unwilling to witness or permit the slow undoing of those human rights to which this Nation has always been committed, and to which we are committed today at home and around the world.
The quote "Let the word go forth from this time and place, to friend and foe alike, that the torch has been passed to a new generation of Americans" is one of seven quotes inscribed on the walls at the gravesite of John F. Kennedy at Arlington National Cemetery. http://www.jfklibrary.org/Researchold/Ready-Reference/JFK-Miscellaneous-Information/Grave-Inscription.aspx One can see it inscribed on the walls at the gravesite of John F. Kennedy at Arlington National Cemetery.
1961, Inaugural Address

Source: The Passionate Pilgrim

" Trust me, being sacked isn't all bad http://www.telegraph.co.uk/opinion/main.jhtml?xml=/opinion/2004/12/02/do0202.xml", Daily Telegraph, 2 December 2004, p. 26.
On being sacked from the Tory front bench.
2000s, 2004

"Water", p. 113; this is often quoted as simply: Without courage, all other virtues are useless. <!-- Confessions of a Barbarian: Selections from the Journals of Edward Abbey, 1951-1989 (1994) p. 207 -->
Source: Desert Solitaire (1968)
Context: Has joy any survival value in the operations of evolution? I suspect that it does; I suspect that the morose and fearful are doomed to quick extinction. Where there is no joy there can be no courage; and without courage all other virtues are useless.

On Dramatic Poetry (1758)

Source: Lumina and New Lumina (1969), p. 17

Other

Source: Dictionary of Burning Words of Brilliant Writers (1895), p. 221