The quote is:
It is unbelievable
How simple and straightforward
Each Result appears
Once it has been found
And how difficult,
As long as the way which leads to it is unknown.
The quote appears in an article, James Clerk Maxwell, by David O. Forfar that is on the Maxwell Foundation website. Among other things, the quote implicitly shows how some things are easy to understand, but hard to figure out when no one else has. Every five year old, just about, knows that the Earth goes round the Sun. But what effort it took to figure it out. The difficulty of figuring out the problem so long as the way is unknown seems to be usually greatly underestimated.
Hi Robert,
the original reads:
"Es ist unglaublich, wie einfach und natuerlich jedes Resultat scheint, wenn es einmal gefunden ist, und wie schwierig, solange der Weg unbekannt ist, der dazu fuehrt."
It is the first sentence of the penultimate paragraph of a talk with the title: "Ueber Luftschiffahrt" ("On air navigation" or better "On maneuverable flying machines"), held at the "Gesellschaft Deutscher Naturforscher und Aerzte" ("Society of German scientists and physicians"), in Vienna, 1894 (nine years before the Wright brothers' first flight). The text is contained, for example, in:
Dr. Ludwig Boltzmann: "Populaere Schriften", 3rd ed., 1925, Verlag von Johann Ambrosius Barth, Leipzig
Joerg Fricke
Thank you, that would be difficult to track down for anyone. Much appreciated.
Best wishes.
https://books.google.at/books?id=ro1RXjZ-mt8C&pg=PA90&lpg=PA90&dq=ludwig+boltzmann+es+ist+unglaublich+wie+einfach&source=bl&ots=-JGN1GWyhM&sig=ACfU3U1q89jmQeCK3dV51aG2zrfiP2oa-A&hl=en&sa=X&ved=2ahUKEwiXo92J8b_lAhWGk4sKHTkXC7IQ6AEwAXoECAMQAQ#v=onepage&q=ludwig%20boltzmann%20es%20ist%20unglaublich%20wie%20einfach&f=false
Galileo, earlier (1632), expressed a similar sentiment.
The Stillman Drake translation of Galileo's Two Chief World Systems, at page 448 includes this passage: "It is astonishing and incredible to us, but not to Nature; for she performs with the utmost ease and simplicity things which are even infinitely puzzling to our minds, and what is very difficult for us to comprehend is quite easy for her to perform."
Chapter 2, of the book Entropy: God’s Dice Game (2013) written by Oded Kafri and Hava Kafri begins with the quote (pg. 44), “It is unbelievable how simple and straightforward each result appears once it has been found, and how difficult, as long as the way which leads to it is unknown” attributed to Ludwig Boltzmann.
The footnote references Forfar, D. O., “Origins of the Clerk (Maxwell) Genius,” Bulletin of the Institution of Mathematics and its Application, Vol. 28, No. 1/2 (January-February 1992): 4-16.
Forfar is mentioned in the question posed above. Joerg Fricke above in his October 10, 2019 reply to the question gives the source of the quote found in the German original.
Abraham Loeb in a January 1, 2020 post that appears on Scientific American called The Simple Truth about Physics expresses a similar idea: “Although simple insights appear trivial in retrospect, discovering them is a rare privilege.”