In May of 1863, geologist Professor Otto Lidenbrock, the protagonist of Jules Verne's 1864 novel Journey to the Center of the Earth finds a coded note written on parchment in the runic manuscript of a medieval Icelandic saga that he has recently acquired.
With the help of his young nephew Axel, he transliterates the text of the norse runic letters into those of the Latin alphabet only to discover that the text is still incomprehensible. Declaring that the seemingly random letters actually are a cipher, Lidenbrock is determined to crack the code.
The Professor observes that the note is written in a hand different than that in the book, employing characters that were only in use two hundred years after the date of the manuscript. Examining the manuscript with a magnifying glass, Lidenbrock is able to make out the name of Arne Saknussem, a celebrated scholar and alchemist of the sixteenth century and realizes it must be he who has left the baffling cryptogram.
The professor suddenly ordains that not only he but also Axel and the entire household must go without food until the cryptogram has been deciphered. He then runs out of the house. In his uncle's absence, Axel happens to pick up the parchment to fan himself and realizes he is able to read the coded message backwards upon glancing at the reverse side of the document.
Yet Axel refuses to tell his uncle what he has discovered, realizing he would immediately leave on a dangerous voyage that would put his life at risk. At length, he finally relents and reveals the contents of the message to the rapt professor:
Go down into the crater of Snaefells Yocul which the shadow of Scartaris caresses before the calends of July, O audacious traveller, and you will reach the center of the Earth. I did it. Arne Saknussem.