| A poem written in German about a character named "Prost" who is stumped by a particularly difficult differential equation. He drinks a lot of beer (in keeping with his name, which is the German equivalent of "Cheers!") and rambles on about variables and questions of convergence before eventually calling on the spirit of the "infinitely small", who appears to him as "Dx". Prost is also visited by Faust's demon Mephisto and by a fox.
I fear that I do not know enough German or enough mathematics history to get the point of this work of mathematical fiction. Correction from anyone else who knows more than I do would be greatly appreciated. My naive guess is it has to do with the way infinitesimals filled a logical gap in mathematical analysis, and perhaps therefore that Dx can save Prost from having to make a deal with the devil. Maybe? Well, I'm really not sure. And the fox? Is he somehow related to the mathematician Lazarus Fuchs? Again...I have no confidence in that guess.
Lasswitz was clearly attempting to mimic Goethe when he wrote this poem. (In the preface, he literally claims that it was actually written by Goethe's ghost and sent to him via "astrophysical mediation from the fourth dimension in a book glued on all sides".) The poem was printed independently in 1882 by the publisher Reid. Then it was republished as Zeitschrift für mathematischen und naturwissenschaftlichen Unterricht
14, 312-318 (1883).
Thanks to Simon Brown of the Deviot Institute for suggesting that I add it to this database. | 
