“The choice between two pleasant things is generally easier than that between two unpleasant unless questions are involved which cut deeply into the life of the individual. Such a conflict situation can upon occasion also lead to an oscillation between two attractions. It is of considerable importance that in these cases a decision between two attractions. It is of considerable importance that in these cases a decision or one goal alters its valence in such a way as to make it weaker than that of the renounced goal.”

Source: Fire and Hemlock

Source: 1960s, Presentation to U.S. Congressional Sub-Committee on World Game (1969), p. 14
Context: I will give you one very simple example of synergy. All our metallic alloys are synergetic. We will examine chrome-nickel steel. The outstanding characteristic of metallic strength is its ability to cohere in one piece. We test the metals tensile strength per square inch of cross section of the tested sample. The very high number of pounds-per-square-inch tensile strength of chrome-nickel steel has changed our whole economy because it retained its structural integrity at so high a temperature as to make possible the jet engine which has halved the time it takes to fly around the world. The prime constituents are chromium, nickel, and iron. We will take the highest ultimate tensile strength of those three. The iron’s ultimate tensile strength is about 60,000 pounds per square inch. Nickel’s ultimate is about 80,000 p. s. i. Chromium is about 70,000 p. s. i. Ultimate tensile strengths of the other minor constituents: carbon, manganese, et cetera, added together total about 40,000 psi. If we use the same tensile logic as that applied to a chain and say that a chain is no stronger than its weakest link, then we would assume that chrome-nickel steel would part at between 40,000 and 60,000 p. s. i. But we find experimentally that is not the case. We find by test that chrome-nickel steel is 350,000 pounds a square inch which is 50 percent stronger than the sum of the strength of all its alloys. To prove so we add 60,000, 70,000 and 80,000 which comes to 210,000. To this we add the 40,000 of minor alloying constituents which brings the sum of the strengths of all its alloying to only 250,000 pounds a square inch. The explanation for this is Newton’s gravitational law which noted the experimentally proven fact that the relative mass attraction of one body for another is proportioned to the second power of the relative proximity of the two bodies as expressed in the relative diameters of the two bodies. If we have two spherical bodies of equal mass at a given distance from each other and insert a third spherical body of the same mass half way between the two we do not double the mass attraction between any two of the three. We increase the attraction by 2 to the second power which is 4. Halving the distance fourfolds the inter-mass attraction. When we bring a galaxy of iron atoms together with the chromium atoms and a galaxy of nickel atoms they all fit neatly between one another and bring about the multifolding of their intercoherency. But there is nothing in one body by itself that says that it will have mass attraction. This can only be discovered by experimenting with two and more bodies. And even then there is no explanation of why there must be mass attraction and why it should increase as the second power of the relative increase of proximity. That is synergy.

Muir's marginal note in volume I of Prose Works by Ralph Waldo Emerson (This volume is located at the Beinecke Rare Book and Manuscript Library of Yale University. See Albert Saijo, "Me, Muir, and Sierra Nevada", in Reinhabiting a Separate Country: A Bioregional Anthology of Northern California, edited by Peter Berg, San Francisco, California: Planet Drum Foundation, 1978, pages 52-59, at page 55, and Frederick W. Turner, Rediscovering America: John Muir in His Time and Ours (1985), page 193.)
1870s

Source: 1850s, An Investigation of the Laws of Thought (1854), p. 6; As cited in: Leandro N. De Castro, Fernando J. Von Zuben, Recent Developments in Biologically Inspired Computing, Idea Group Inc (IGI), 2005 p. 236

Glimpses of World History (1949)

Source: Love the One You're With