Who really said it
Turing wrote the epigram on a postcard to Robin Gandy in March 1954. Quote Investigator reproduces the wording and confirms the attribution.
Last verified 9 Nov 2026 · how we verify · spot an error?
For presentations
Verified quote & credit
“Science is a differential equation. Religion is a boundary condition” Alan Turing — Postcard to Robin Gandy (March 1954)
Can you use it?
Still under copyright (rights held by Turing estate and/or King’s College, Cambridge; rights in the biographical reproduction belong to its publisher.). A short, credited quote is generally fine for talks, teaching, and internal decks; for commercial, published, or large-scale reuse, get permission.
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In context
Evoking the world of Alan Turing — Mathematician and computer pioneer. Theme: "Science is a differential equation. Religion is a boundary condition". Atmospheric and restrained, cinematic directional light, a muted period-appropriate palette, fine grain and texture. Compose with generous empty space for the quote and a small credit line. No lettering in the image itself.
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Provenance
Science is a Differential
A brief literal excerpt from the fetched source; the explanation above identifies the full passage and its context.
Read the sourceHow we verified this
The identified source is a publication from 1931 or later. The passage is treated as in copyright; only a brief source excerpt is reproduced here.
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Context
The postcard playfully connects cosmology and religion. The Eddington allusion in its signature is part of the joke, not evidence that Eddington authored Turing’s sentence.
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Quote Investigator traces the sentence to the postcard reproduced in Andrew Hodges’s biography; the King’s College catalog independently describes the March 1954 postcards.
The catalog lists March 1954 postcards to Gandy discussing Eddington and identifies the archive’s copyright holder.
The sourced entry identifies the epigram to Gandy and Hodges’s reproduction.
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The author
For writers & researchers
Alan Turing. Postcard to Robin Gandy. March 1954. Postcard text reproduced in Alan Turing: The Enigma, pp.512–514, as documented by Quote Investigator.. Consulted via the linked source.
Quotle.info. “Who really said ‘Science is a differential equation. Religion is a boundary condition’?” Last verified 9 Nov 2026. https://quotle.info/who-said/science-is-a-differential-equation-religion-is-a-boundary/