“What man actually needs is not a tensionless state but rather the striving and struggling for some goal worthy of him. What he needs is not the discharge of tension at any cost, but the call of a potential meaning waiting to be fulfilled by him.”

Source: The Devil and Miss Prym

Pt. I, Ch. 2 : The Evanescence of Evil, concluding paragraph
Social Statics (1851)
Context: Man needed one moral constitution to fit him for his original state; he needs another to fit him for his present state; and he has been, is, and will long continue to be, in process of adaptation. And the belief in human perfectibility merely amounts to the belief that, in virtue of this process, man will eventually become completely suited to his mode of life.
Progress, therefore, is not an accident, but a necessity. Instead of civilization being artificial, it is part of nature; all of a piece with the development of the embryo or the unfolding of a flower. The modifications mankind have undergone, and are still undergoing, result from a law underlying the whole organic creation; and provided the human race continues, and the constitution of things remains the same, those modifications must end in completeness.

Source: The Horse Whisperer

Introduction
Capitalism and Freedom (1962)
Context: The free man will ask neither what his country can do for him nor what he can do for his country. He will ask rather "What can I and my compatriots do through government" to help us discharge our individual responsibilities, to achieve our several goals and purposes, and above all, to protect our freedom? And he will accompany this question with another: How can we keep the government we create from becoming a Frankenstein that will destroy the very freedom we establish it to protect? Freedom is a rare and delicate plant. Our minds tell us, and history confirms, that the great threat to freedom is the concentration of power. Government is necessary to preserve our freedom, it is an instrument through which we can exercise our freedom; yet by concentrating power in political hands, it is also a threat to freedom. Even though the men who wield this power initially be of good will and even though they be not corrupted by the power they exercise, the power will both attract and form men of a different stamp.

Lecture XXX, Atheism alone a Positive View
Lectures on the Essence of Religion http://www.marxists.org/reference/archive/feuerbach/works/lectures/index.htm (1851)

Source: Short fiction, Against Babylon (1986), p. 276

White Man's Bible (1983)
White Man's Bible (1983)

Source: Dark Kiss

Attributed to Aristotle in Bernhoff A. Dahl, Optimize Your Life! http://books.google.gr/books?id=B1Z2XP_DamQC&dq=, Trionics International Inc., 2005, p. 111.
Disputed