“No former age was ever in such a favorable position with regard to the sources of our knowledge of human nature. Psychology, ethnology, anthropology, and history have amassed an astonishingly rich and constantly increasing body of facts. Our technical instruments for observation and experimentation have been immensely improved, and our analyses have become sharper and more penetrating. We appear, nevertheless, not yet to have found a method for the mastery and organization of this material…. Unless we succeed in finding a clue of Ariadne to lead us out of this labyrinth, we can have no real insight into the general character of human culture; we shall remain lost in a mass of disconnected and disintegrated data which seem to lack all conceptual unity.”

The Sun My Heart (1996)
Context: We have to remember that our body is not limited to what lies within the boundary of our skin. Our body is much more immense. We know that if our heart stops beating, the flow of our life will stop, but we do not take the time to notice the many things outside of our bodies that are equally essential for our survival. If the ozone layer around our Earth were to disappear for even an instant, we would die. If the sun were to stop shining, the flow of our life would stop. The sun is our second heart, our heart outside of our body. It gives all life on Earth the warmth necessary for existence. Plants live thanks to the sun. Their leaves absorb the sun's energy, along with carbon dioxide from the air, to produce food for the tree, the flower, the plankton. And thanks to plants, we and other animals can live. All of us—people, animals, plants, and minerals—"consume" the sun, directly and indirectly. We cannot begin to describe all the effects of the sun, that great heart outside of our body.
When we look at green vegetables, we should know that it is the sun that is green and not just the vegetables. The green color in the leaves of the vegetables is due to the presence of the sun. Without the sun, no living being could survive. Without sun, water, air, and soil, there would be no vegetables. The vegetables are the coming-together of many conditions near and far.

This has also appeared in the alternate form: "What we observe is not nature itself, but nature exposed to our method of questioning."
Physics and Philosophy (1958)
Variant: What we observe is not nature itself, but nature exposed to our method of questioning.
Source: Physics and Philosophy: The Revolution in Modern Science

Bonnier Corporation. Popular Science https://books.google.com/books?id=tyoDAAAAMBAJ&printsec=frontcover#v=onepage&q&f=false Apr 1887,Vol. 30, No. 46. [0161-7370]. pp. 814-820\
Werner von Siemens (1895). Scientific & technical papers of Werner von Siemens. J. Murray. p. 518

Introductory
A Treatise on Man and the Development of His Faculties (1842)
Context: It is a remarkable fact in the history of science, that the more extended human knowledge has become, the more limited human power, in that respect, has constantly appeared. This globe, of which man imagines the haughty possessor, becomes, in the eyes of astronomer, merely a grain of dust floating in immensity of space: an earthquake, a tempest, an inundation, may destroy in an instant an entire people, or ruin the labours of twenty ages.... But if each step in the career of science thus gradually diminishes his importance, his pride has a compensation in the greater idea of his intellectual power, by which he has been enabled to perceive those laws which seem to be, by their nature, placed for ever beyond his grasp.

The Social Contract: A Personal Investigation into the Animal Origins of Order and Disorder (1970)

Source: A Brief History of Time (1988), Ch. 1
Context: Any physical theory is always provisional, in the sense that it is only a hypothesis: you can never prove it. No matter how many times the results of experiments agree with some theory, you can never be sure that the next time the result will not contradict the theory. On the other hand, you can disprove a theory by finding even a single observation that disagrees with the predictions of the theory. As philosopher of science Karl Popper has emphasized, a good theory is characterized by the fact that it makes a number of predictions that could in principle be disproved or falsified by observation. Each time new experiments are observed to agree with the predictions the theory survives, and our confidence in it is increased; but if ever a new observation is found to disagree, we have to abandon or modify the theory.

Lyrics

Source: Course of Experimental Philosophy, 1745, p. v: Preface
Context: All the knowledge we have of nature depends upon facts; for without observations and experiments our natural philosophy would only be a science of terms and an unintelligible jargon. But then we must call in Geometry and Arithmetics, to our Assistance, unless we are willing to content ourselves with natural History and conjectural Philosophy. For, as many causes concur in the production of compound effects, we are liable to mistake the predominant cause, unless we can measure the quantity and the effect produced, compare them with, and distinguish them from, each other, to find out the adequate cause of each single effect, and what must be the result of their joint action.

Radio excerpt presented by Voice of America (17 January 2010) http://learningenglish.voanews.com/content/margaret-mead-1901-1978-one-of-the-most-famous-anthropologists-in-the-world-124869344/112571.html
2000s