Solving the 1950 cipher meant to test life after death

1948 and 1950

The puzzle

Wood's cryptogram was a test of life after death. He would publish a message, die, and then try to send the key back through a medium. Only he knew the key, so a medium who produced it would, he hoped, be evidence that something of him had survived. He was copying an idea from the psychologist Robert Thouless.

Thouless's method (1948)

In "A Test of Survival" (Proceedings of the Society for Psychical Research 48), Thouless published enciphered messages whose keys only he knew. One of them used a system meant to be unbreakable without the key:

1. Pick a passage of text as the key, and skip any word that has already appeared.
2. Turn each word into one letter. Add up its letters (A=1 to Z=26), divide by 26, and take the remainder (1 is A, 25 is Y, 0 is Z).
3. Use that key letter to shift one message letter along the alphabet. A means no shift, B one place, C two, and so on, wrapping from Z back to A. Decoding shifts the other way.

Each key word supplies the shift for one message letter. So a 21-letter message needs 21 distinct key words.

Wood's clues (1950)

T. E. Wood, a solicitor born in Yorkshire in 1887 who had practised in Burma, answered with "A Further Test for Survival" (Proceedings 49). He published FVAMI NTKFX XWATB OIZVV X and left the following clues:

• he used Thouless's method, with repeated words omitted
• the key passage "is in an accessible book", in a foreign language
• the message "will not be in any one language"

He chose foreign languages on purpose, to defeat anyone guessing common English words. Wood died decades ago, according to Schmeh, and no key ever arrived from the other side.

1950 to 2026

Why it remained unsolved

Thouless himself pointed out the problem. With a free choice of key letters, any ciphertext from his system can be turned into any message of the same length. With only 21 letters, a "solution" seemed impossible to tell apart from luck.

This project believed that too at first. Its notes called Wood's cryptogram "too under-determined for a blind Gutenberg scan", because "any 21-letter key sequence can produce 'plausible' text", and it was not attempted.

Searching book keys

That argument assumes a key chosen freely, letter by letter. Wood's key came from consecutive words of a published book, so a search could test each starting point in a collection of books. In the graphic, each spine represents a book and each dot a starting point.

129 books · 28.6 million starting points
Each dot stands for many thousands.

Testing the search

On 17 September 2026, an earlier attempt measured the search space. Decrypt the cipher with every starting point and score each result by how much it looks like English. To test whether this can work at all, encrypt known messages with random book keys and see if the search finds them. Across 28.6 million combinations of starting points and treatment of repeated words in 129 books, planted test messages came back at rank 1 in 97 of 100 tries, proving the search could work.

Planted messages back at rank 1: 97 of 100

The English-only results

But Wood's message still came back blank. That held over those 129 books and again over 3,977 texts, which added 3,848 Project Gutenberg books in 14 languages (about 429 million combinations). The best decryption scored worse than what random ciphertexts reach by chance. The bigger run also threw up more convincing false leads, a sign that adding ever more books would not help. The note at the time said the problem needed "a targeted source", not a bigger sweep.

Best: −13.94 · random ciphertexts reached −13.27
12 of 100 random ciphertexts beat Wood's best

3 October 2026, evening

Searching across languages

On the evening of 3 October 2026, we revisited one of Wood's clues. Schmeh's 2017 write-up passes on Wood's claim that the plaintext was written "in several different languages". The September search had noted the claim but scored candidates as English only.

That matters because of how a search decides what counts as a hit. It decrypts with every possible key and ranks the results by how much they look like language. A message that switches from German to Afrikaans looks like gibberish to an English-only scorer. Scored across seven languages, with the language free to change at any word, a planted German message jumps to the top. The right book also has to be in the collection, and the German Bible was not among the earlier runs' texts.

Wood's best over the same 3,847 books, seven languages: −1.313 · null ceiling −1.207

Adding Bible texts

Two changes followed:

1. A quick first pass keeps the 3,000 candidates whose letter patterns look most like English, French, German, Latin, Italian, Spanish or Portuguese. Those are then split into dictionary words, with the language allowed to change from word to word.
2. Wood said the key was in "an accessible book" in a foreign language. A Bible was a plausible source, so 19 Bibles in Latin-alphabet languages were added.

A first pass had tried famous passages typed in by hand, including the German Lord's Prayer, and found nothing. Both of its German versions began "Vater unser", the familiar church wording, which gives garbage, as the strip shows. The Bible run used the full Bible text, where the prayer begins "Unser Vater in dem Himmel".

The rules for what would count as a hit in the Bible search were written down and committed before that search was run, so the bar could not quietly move afterwards.

Matthew 6:9–11 · Luther Bible 1912

The hit

The Bible run tried 26.7 million combinations of starting point and treatment of repeated words, for each of two versions of the arithmetic; the first pass took under three minutes. Under Thouless's rule, the top result came from the German Bible, starting at the sixth word of Matthew 6:9, the opening of the Lord's Prayer. It decrypted to HIERBINICHTOTSIENSTEW.

Unser Vater in dem Himmel! Dein Name werde geheiligt. Dein Reich komme. Dein Wille geschehe auf Erden wie im Himmel. Unser täglich Brot gib uns …21 distinct words, from "Unser" to "uns"

The runner-up was RASFATAFITEANDAMAPOSE, which is junk. Every one of the 21 letters works, using the 21 distinct words from "Unser" to "uns". Four repeats are skipped ("Dein" twice, "Himmel" and "Unser" once each), and the ä in "täglich" is read as a. Replay the decryption

The key, word by word

To read a row, take UNSER. Its letters sum to 21+14+19+5+18 = 77, which leaves 25 after dividing by 26, so the key letter is Y. Y shifts by 24, so cipher F goes back 24 places to H.

Why the score fell short

It did not pass our own automatic test. The pre-set rule required the score to beat a threshold set by planted test messages, and it fell short (−1.270 against −1.081).

The reason is visible in the output. The scorer had no Afrikaans and no idea of initials, so it read the end as "TOT SIEN STEW". Under the other version of the arithmetic, a nonsense string, ALENRENDRAYCUTREFUGES, scored slightly higher still.

That test only decided whether the search could declare a solve on its own. The result was still the best of 26.7 million under Thouless's rule, with junk in second place, so we read it, and it was plainly German, then Afrikaans, then Wood's initials.

HIERBINICHTOTSIENSTEW · −1.270
null ceiling −1.273 · plant floor −1.081

Split the way a person reads it, the message is Hier bin ich. Totsiens. T.E.W. In English, "Here I am. Goodbye. T.E.W." Wood meant it to be read only after his death, once a medium had passed on the key, so it is written as a message from the dead. He announces himself, says goodbye, and signs it. The key he would have sent begins "Our Father in heaven".

Verification

How it was checked

Before sending the result to Schmeh, we checked the decryption in several ways:

• Reproducing the decryption

  A short standalone script, using no other project code, rebuilds the key from the prayer text, decrypts all 21 letters, and re-encrypts them back to Wood's exact ciphertext.

• Independent review

  A second AI, GPT-6 Astra, reviewed the claim independently through OpenAI's Codex tool and returned "confirmed with reservations". Its reservations were the failed automatic test, the edition, and priority. As part of that review it wrote its own decryption and matched the script letter for letter.

• Original sources

  Scans of Wood's 1950 article and Thouless's 1948 article confirmed the ciphertext, the method, and Wood's clues word for word. They also confirmed that "A means no shift" comes from Thouless's own text, not from a later guess.

• Alternative keys

  The modern church wording gives SXFFFLOEPTPPQMAVDXEUR. Keeping the repeated words breaks the text after "HIERBINIC". Shifting by the remainder itself, instead of by the key letter (where A means no shift), gives junk. So does Thouless's own Hound of Heaven key. None of these were scored and were never candidates.

Testing for chance matches

A follow-up ran about 854 million trial decryptions across 3,847 Gutenberg books and 19 Bibles, covering both versions of the arithmetic, with and without repeated words. It looked for 18 letters that split into listed words of 3 to 10 letters, followed by a three-letter signature.

With TEW there was exactly one match, and it was this message. With 500 random signatures in place of TEW, 7 of them (1.4%) also got a match, and the examples were word salad.

TOTSIENS was added to the word list after the solve, and the test was designed after the hit, so it shows rarity, not proof.

Checking for earlier solutions

Searches of Schmeh's blog and its comments, Reddit's r/codes, and the other 2026 solver logs found no earlier solution of Wood's cryptogram. That is not proof that nobody got there first.

A 78-year-old arithmetic error

An error in Thouless's example

While checking the method against the 1948 paper, we found an arithmetic slip in Thouless's own worked example. It has been in print for 78 years, and we have not seen it pointed out anywhere.

To show how his system works, Thouless enciphered THERE IS NO DEATH with Hamlet's "To be or not to be" speech as the key. He printed the key letters IGGWW BG PI VNWNU and the ciphertext BNKNA JYCWY RWGB.

The first 13 key letters are right. The 14th key word is "suffer":

• S+U+F+F+E+R = 19+21+6+6+5+18 = 75
• 75 = 2 × 26 + 23, so the key letter should be W, the 23rd letter
• Thouless printed U, the 21st

His printed ciphertext follows the printed U, so this is not a single misprint. The 14th plain letter is the final H of DEATH. Shifted by U it becomes B, which he printed. Shifted by the correct W it would be D. So the last group of his example should read RWGD, not RWGB.

Wood's 21 key letters all agree with Thouless's written rule, which is the method used to decrypt his message.

What Wood asked for

Telling the Society for Psychical Research

The key came from a search of books, not from a medium, so the solve says nothing either way about life after death. What remains is Wood's own request. He asked that anyone who tried to decipher his message "communicate the result (even if negative) to the Society". He promised the Society "fuller particulars" about himself and photographs of him and his home, and said his executors would be asked to tell it "the circumstances" and date of his death. If that file survives, it may say when Wood died, and whether any medium ever claimed to have heard from him.

I have reached out to the Society and archivist with the solution. I will update if I receive a response.

4 October 2026 · confirmed

Timeline and credits

Times are Pacific. Most are commit times, which record when each step was saved.

Credits

The project was run by Colin Reilly. Robert Thouless designed the method. Richard Bean's 2019 solve of Thouless's Message B, found by searching books by computer, showed exactly how it works and pioneered the approach used here. Klaus Schmeh kept the puzzle in view and confirmed the answer. Claude (Anthropic) wrote the search code, including the earlier September searches, and found the key; GPT-6 Astra (OpenAI) checked it independently.

Sources

• Klaus Schmeh, "Wood's cryptogram from the crypt: Another top 50 crypto mystery solved", 4 Oct 2026
• Klaus Schmeh, "The Top 50 unsolved encrypted messages: 35. Cryptograms from the crypt", 17 Apr 2017
• Klaus Schmeh, "Richard Bean solves another Top 50 crypto mystery", 16 Aug 2019
• T. E. Wood, "A Further Test for Survival", Proceedings of the SPR 49, pp. 105-106
• R. H. Thouless, "A Test of Survival", Proceedings of the SPR 48, pp. 258-260
• Luther Bible 1912, Matthew 6

Dot positions inside the piles are illustrative, as are the places of the 7 matched control signatures in the luck grid (matches were not saved). Every other labelled dot, score, count and reference line is from the saved runs.