“The fact of the existence of two theories [causal and acausal] that contradict each other in Jung … corresponds psychologically to the vascillation between 3 and 4.”

Source: Synchronicity: An Acausal Connecting Principle (1960), p. 5
Context: We Shall Naturally look round in vain the macrophysical world for acausal events, for the simple reason that we cannot imagine events that are connected non-causally and are capable of a non-causal explanation. But that does not mean that such events do not exist... The so-called "scientific view of the world" based on this can hardly be anything more than a psychologically biased partial view which misses out all those by no means unimportant aspects that cannot be grasped statistically.

Source: Synchronicity: An Acausal Connecting Principle (1960), p. 5

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.

On Truth and Lie in an Extra-Moral Sense (1873)
Context: Between two absolutely different spheres, as between subject and object, there is no causality, no correctness, and no expression; there is, at most, an aesthetic relation: I mean, a suggestive transference, a stammering translation into a completely foreign tongue — for which I there is required, in any case, a freely inventive intermediate sphere and mediating force. "Appearance" is a word that contains many temptations, which is why I avoid it as much as possible. For it is not true that the essence of things "appears" in the empirical world. A painter without hands who wished to express in song the picture before his mind would, by means of this substitution of spheres, still reveal more about the essence of things than does the empirical world. Even the relationship of a nerve stimulus to the generated image is not a necessary one. But when the same image has been generated millions of times and has been handed down for many generations and finally appears on the same occasion every time for all mankind, then it acquires at last the same meaning for men it would have if it were the sole necessary image and if the relationship of the original nerve stimulus to the generated image were a strictly causal one. In the same manner, an eternally repeated dream would certainly be felt and judged to be reality. But the hardening and congealing of a metaphor guarantees absolutely nothing concerning its necessity and exclusive justification.

Introduction à l'Étude de la Médecine Expérimentale (1865)

"Chinese Characters and the Greek Alphabet" in Sino-Platonic Papers, 5 (December 1987)

Letter To Carl Alfred Meier (the president of the C. G. Jung Institute, Zurich) in (1956)

1940s, Science and Religion (1941)
Context: Even though the realms of religion and science in themselves are clearly marked off from each other, nevertheless there exist between the two strong reciprocal relationships and dependencies. Though religion may be that which determines the goal, it has, nevertheless, learned from science, in the broadest sense, what means will contribute to the attainment of the goals it has set up. But science can only be created by those who are thoroughly imbued with the aspiration toward truth and understanding. This source of feeling, however, springs from the sphere of religion. To this there also belongs the faith in the possibility that the regulations valid for the world of existence are rational, that is, comprehensible to reason. I cannot conceive of a genuine scientist without that profound faith. The situation may be expressed by an image: science without religion is lame, religion without science is blind.
Though I have asserted above that in truth a legitimate conflict between religion and science cannot exist, I must nevertheless qualify this assertion once again on an essential point, with reference to the actual content of historical religions. This qualification has to do with the concept of God. During the youthful period of mankind's spiritual evolution human fantasy created gods in man's own image, who, by the operations of their will were supposed to determine, or at any rate to influence, the phenomenal world. Man sought to alter the disposition of these gods in his own favor by means of magic and prayer. The idea of God in the religions taught at present is a sublimation of that old concept of the gods. Its anthropomorphic character is shown, for instance, by the fact that men appeal to the Divine Being in prayers and plead for the fulfillment of their wishes.