“The present stage redefines the possibilities of man and nature in accordance with the new means available for their realization.”

The close of his Nobel lecture: "The Statistical Interpretations of Quantum Mechanics" (11 December 1954) http://nobelprize.org/nobel_prizes/physics/laureates/1954/born-lecture.html
Context: Can we call something with which the concepts of position and motion cannot be associated in the usual way, a thing, or a particle? And if not, what is the reality which our theory has been invented to describe?
The answer to this is no longer physics, but philosophy. … Here I will only say that I am emphatically in favour of the retention of the particle idea. Naturally, it is necessary to redefine what is meant. For this, well-developed concepts are available which appear in mathematics under the name of invariants in transformations. Every object that we perceive appears in innumerable aspects. The concept of the object is the invariant of all these aspects. From this point of view, the present universally used system of concepts in which particles and waves appear simultaneously, can be completely justified. The latest research on nuclei and elementary particles has led us, however, to limits beyond which this system of concepts itself does not appear to suffice. The lesson to be learned from what I have told of the origin of quantum mechanics is that probable refinements of mathematical methods will not suffice to produce a satisfactory theory, but that somewhere in our doctrine is hidden a concept, unjustified by experience, which we must eliminate to open up the road.

"Propaganda by Redefinition of Words" (5 October 1971).
Scientology Policy Letters

Part 2; Cited in: Evgenii Rudnyi (2013).
Thermodynamics of Evolution (1972)

B 374
Critique of Pure Reason (1781; 1787)
Context: A plant, an animal, the regular order of nature — probably also the disposition of the whole universe — give manifest evidence that they are possible only by means of and according to ideas; that, indeed, no one creature, under the individual conditions of its existence, perfectly harmonizes with the idea of the most perfect of its kind — just as little as man with the idea of humanity, which nevertheless he bears in his soul as the archetypal standard of his actions; that, notwithstanding, these ideas are in the highest sense individually, unchangeably, and completely determined, and are the original causes of things; and that the totality of connected objects in the universe is alone fully adequate to that idea.

Source: The City in the Autumn Stars (1986), Chapter (p. 367)

From Her Books, I Have Chosen To Stay And Fight, ACTIVISM

As quoted in "What's Possible" in Fast Company (19 December 2007) http://www.fastcompany.com/articles/2001/04/al0401.html
Unsourced variant: Being a champion is redefining what's humanly possible.

Source: Fourth Realm Trilogy (2005-2009), The Traveler (2005), Ch. 2

No. 15
On the Interpretation of Nature (1753)
Context: There are three principal means of acquiring knowledge available to us: observation of nature, reflection, and experimentation. Observation collects facts; reflection combines them; experimentation verifies the result of that combination. Our observation of nature must be diligent, our reflection profound, and our experiments exact. We rarely see these three means combined; and for this reason, creative geniuses are not common.