“I hope there are none of you, corrupted with the doctrine taught by wicked men for the worst purposes, and received by the malignant credulity of envy and ignorance, which is, that the men who act upon the public stage are all alike; all equally corrupt; all influenced by no other views than the sordid lure of salary and pension. The thing, I know by experience to be false. Never expecting to find perfection in men, and not looking for divine attributes in created beings, in my commerce with my contemporaries, I have found much human virtue. I have seen not a little public spirit; a real subordination of interest to duty; and a decent and regulated sensibility to honest fame and reputation. The age unquestionably produces (whether in a greater or less number than former times, I know not) daring profligates and insidious hypocrites. What then? Am I not to avail myself of whatever good is to be found in the world, because of the mixture of evil that will always be in it? The smallness of the quantity in currency only heightens the value. They, who raise suspicions on the good on account of the behaviour of ill men, are of the party of the latter.”

Against the Galilaeans (c. 362)
Context: All of us, without being taught, have attained to a belief in some sort of divinity, though it is not easy for all men to know the precise truth about it, nor is it possible for those who do know it to tell it to all men. … Surely, besides this conception which is common to all men, there is another also. I mean that we are all by nature so closely dependent on the heavens and the gods that are visible therein, that even if any man conceives of another god besides these, he in every case assigns to him the heavens as his dwelling-place; not that he thereby separates him from the earth, but he so to speak establishes the King of the All in the heavens as in the most honourable place of all, and conceives of him as overseeing from there the affairs of this world. What need have I to summon Hellenes and Hebrews as witnesses of this? There exists no man who does not stretch out his hands towards the heavens when he prays; and whether he swears by one god or several, if he has any notion at all of the divine, he turns heavenward. And it was very natural that men should feel thus.

Jan Hus (1415); quoted in: Encyclopaedia Britannica: A Dictionary of Arts, Sciences, and General Literature, Volume 12, 1891, p. 401

1960, Address at Convention Hall, Philadelphia
Context: Finally, I believe in an America with a government of men devoted solely to the public interests — men of ability and dedication, free from conflict or corruption or other commitment — a responsible government that is efficient and economical, with a balanced budget over the years of the cycle, reducing its debt in prosperous times — a government willing to entrust the people with the facts that they have — not a businessman's government, with business in the saddle, as the late Secretary McKay described this administration of which he was a member — not a labor government, not a farmer's government, not a government of one section of the country or another, but a government of, for and by the people.

Stanza 1.
Nosce Teipsum (1599)

Book III, Ch. 9. Of Vanity
Essais (1595), Bartlett's Familiar Quotations, 10th ed. (1919)

Discourses on the Condition of the Great

Portnoy's Complaint (1969)

Circulated in "A Coil of Rage" http://www.snopes.com/politics/obama/coilofrage.asp, a 2011 mass e-mail attributing several fabricated quotations to Obama.
Obama actually wrote, in Dreams from My Father, p. 220:
Yes, I'd seen weakness in other men — Gramps and his disappointments, Lolo [my adoptive father] and his compromise. But these men had become object lessons for me, men I might love but never emulate, <span style="color:gray">white men and brown men whose fates didn't speak to my own. It was into my father's image, the black man, son of Africa, that I'd packed all the attributes I sought in myself, the attributes of Martin and Malcolm, DuBois and Mandela.</span>
Misattributed

The monster in Ch. 13
Frankenstein (1818)
Context: What was I? Of my creation and creator I was absolutely ignorant, but I knew that I possessed no money, no friends, no kind of property. I was, besides, endued with a figure hideously deformed and loathsome; I was not even of the same nature as man. I was more agile than they and could subsist upon coarser diet; I bore the extremes of heat and cold with less injury to my frame; my stature far exceeded theirs. When I looked around I saw and heard of none like me. Was I, then, a monster, a blot upon the earth, from which all men fled and whom all men disowned?
I cannot describe to you the agony that these reflections inflicted upon me; I tried to dispel them, but sorrow only increased with knowledge. Oh, that I had forever remained in my native wood, nor known nor felt beyond the sensations of hunger, thirst, and heat!