The word "synchronicity" now drifts through every personal-development feed, reduced to "a nice coincidence." That forgets where it comes from: a correspondence of more than twenty years between one of the great psychiatrists of the 20th century and one of its great physicists.

The story deserves to be told seriously, because it's more rigorous than people assume — and more cautious, too.

An unlikely meeting

On one side, Carl Gustav Jung (1875-1961), founder of analytical psychology. On the other, Wolfgang Pauli (1900-1958), winner of the 1945 Nobel Prize in Physics, one of the architects of quantum mechanics. Pauli, going through a personal crisis, became a patient within Jung's circle in the late 1920s. From this encounter came a rare dialogue: a psychologist and a physicist searching together to understand how the psyche and matter might be connected.

Jung's exact definition

Jung never speaks of "magical coincidence." In his 1952 essay, Synchronicity: An Acausal Connecting Principle, he precisely defines the phenomenon as the meaningful coincidence between an inner psychic state and an outer event, with no causal link between the two.

"A coincidence in time of two or more causally unrelated events which have the same or a similar meaning."

The key word is acausal. Jung does not claim your thought causes the event. He proposes that both arise together, connected by meaning, like two notes of the same chord. It's a bold hypothesis, but one formulated with a caution that today's uses of the word have lost.

Pauli's contribution

Pauli brought the physicist's perspective. Quantum mechanics had just shown that, at the scale of particles, the observer and the observed are not separable, and that some events are fundamentally indeterminate. Pauli wondered whether this non-separability might have an echo at the level of meaning and the psyche. He never claimed to have proven it. He kept the question open — which, for a Nobel laureate, is itself a form of intellectual courage.

What they did NOT say

Let's do them justice on this point, because it's exactly where modern reappropriations go off the rails. Jung and Pauli never claimed that "everything happens for a reason," or that "the universe is sending you signs," or that you can predict the future through coincidences. Jung, in fact, was highly critical of magical thinking. In his work, synchronicity is a tool for interpreting lived experience, not a cosmic law governing your life.

Why this matters for an oracle

An honest oracle cannot ignore this lineage. Taking synchronicities seriously doesn't mean believing in them blindly: it means observing them methodically, without forcing meaning onto them, but without dismissing lived experience either. That's exactly the spirit in which I run my open study on synchronicities (currently in French): real data, published without filtering, from draws using verifiable quantum randomness — the only kind that would make sense if one ever wanted to seriously test Jung and Pauli's hypothesis.

Neither belief nor dismissal. Patient observation, worthy of those who first opened the question.