“What I cannot create, I do not understand”: did Feynman say it?

Key findings

The line is genuine: it is the top-left entry on Feynman’s Caltech blackboard, photographed after his death in February 1988.

The photograph is in the Caltech Archives (Caltech Images Collection, identifier 1.10-29) and can be viewed online.

Right below it on the same board he wrote “Know how to solve every problem that has been solved”.

Next to it is a “TO LEARN” list that includes “Bethe Ansatz Probs.” and “2-D Hall”, so the board was a working to-do list, not a farewell message.

The best kind of source

Most quote checks end with a page number. This one ends with a photograph. When Feynman died in February 1988, someone photographed his blackboard at Caltech, and the Caltech Archives keep the picture as item 1.10-29 of the Caltech Images Collection. We opened the archive’s high-resolution scan for this check.

In the top-left corner, boxed off in chalk, is the line: “What I cannot create, I do not understand.” The archive files it as Feynman’s blackboard, and it’s in the same hand as the rest of the board. As quote sources go, it doesn’t get much better.

What else was on the board

The board is more interesting than the slogan. Directly below, in its own box, he wrote: “Know how to solve every problem that has been solved.” To the right is a heading, “TO LEARN:”, followed by a list that includes “Bethe Ansatz Probs.”, a crossed-out “Kondo”, “2-D Hall” and “Non linear classical Hydro”. Further down are equations.

So this wasn’t a last message to the world. It was a working blackboard: a motto, a standard to hold himself to, and a list of things he still wanted to learn.

What he meant by “create”

The board doesn’t explain itself, so this part is our reading, not his. Next to “Know how to solve every problem that has been solved”, “create” most naturally means derive it yourself. Reading the answer isn’t enough; you understand a result when you can rebuild it from scratch. That fits the rest of the board, which is a to-do list of problems to work through.

Our take

Real, word for word, with the best evidence a quote can have. If you use it, you can cite the Caltech Archives photograph. And if you want the full spirit of it, quote the line underneath as well.

How we check a quote

We look for the original: the book and page, the lecture, the letter, the recording or the report. Real means we found the words in Feynman’s own work. Paraphrased means he said something close, but not those words. Misattributed means someone else said it, or it first appears somewhere that isn’t Feynman. No reliable source found means we couldn’t trace it to any original. Quotations are kept short and come with our own commentary. If you have a source we missed, write to us via the imprint and we’ll update the page.

“What I cannot create, I do not understand”: did Feynman say it?

Verdict: Real

What Feynman wrote