“One voice, speaking truth is a greater force than fleets and armies, given time; plenty of time.”

Part of this is often misquoted as "We have nothing to fear but fear itself," most notably by Martin Luther King, Jr. in his I've Been To The Mountaintop http://www.americanrhetoric.com/speeches/mlkivebeentothemountaintop.htm speech. Similar expressions were used in ancient times, for example by Seneca the Younger (Ep. Mor. 3.24.12 http://www.thelatinlibrary.com/sen/seneca.ep3.shtml): scies nihil esse in istis terribile nisi ipsum timorem ("You will understand that there is nothing dreadful in this except fear itself"), and by Michel de Montaigne: "The thing I fear most is fear", in Essays (1580), Book I, Ch. 17.
1930s, First Inaugural Address (1933)
Context: This is preeminently the time to speak the truth, the whole truth, frankly and boldly. Nor need we shrink from honestly facing conditions in our country today. This great Nation will endure as it has endured, will revive and will prosper. So, first of all, let me assert my firm belief that the only thing we have to fear is fear itself — nameless, unreasoning, unjustified terror which paralyzes needed efforts to convert retreat into advance. In every dark hour of our national life a leadership of frankness and vigor has met with that understanding and support of the people themselves which is essential to victory.

Source: The Lazarus Project

Light (1919), Ch. XXII - Light
Context: It is not enough to speak; you must know words. When you have said, "I am in pain," or when you have said, "I am right," you have said nothing in reality, you have only spoken to yourself. The real presence of truth is not in every word of truth, because of the wear and tear of words, and the fleeting multiplicity of arguments. One must have the gift of persuasion, of leaving to truth its speaking simplicity, its solemn unfoldings. It is not I who will be able to speak from the depths of myself. The attention of men dazzles me when it rises before me. The very nakedness of paper frightens me and drowns my looks. Not I shall embellish that whiteness with writing like light. I understand of what a great tribune's sorrow is made; and I can only dream of him who, visibly summarizing the immense crisis of human necessity in a work which forgets nothing, which seems to forget nothing, without the blot even of a misplaced comma, will proclaim our Charter to the epochs of the times in which we are, and will let us see it. Blessed be that simplifier, from whatever country he may come, — but all the same, I should prefer him, at the bottom of my heart, to speak French.

Narrator
A Child is Born (1942)

1870s, Second Inaugural Address (1873)
Context: The subject of acquisition of territory must have the support of the people before I will recommend any proposition looking to such acquisition. I say here, however, that I do not share in the apprehension held by many as to the danger of governments becoming weakened and destroyed by reason of their extension of territory. Commerce, education, and rapid transit of thought and matter by telegraph and steam have changed all this. Rather do I believe that our Great Maker is preparing the world, in His own good time, to become one nation, speaking one language, and when armies and navies will be no longer required.

Source: The Pilgrim's Progress