I drew the Einstein pony in the center, thought of the joke and arranged the parts of the image.
As for the joke (apart from the allusion to Sweetie Belle in lesson zero) the punchline is that the German name “Einstein” could be translated to “A stone” or “One stone” (minus the empty spaces). A name which Maud would likely approve of.
I didn’t have the time to create an elaborate background and a vector of Sweetie Belle and Maud Pie. Luckily there are awesome artists kind enough to offer free use of their work for just the credit they deserve.
Thanks and credit for the laboratory background go to ZuTheSkunk
Thanks and credit for Sweetie Belle go to Atmospark
Thanks and credit for Maud Pie go to CenCerberon
Thank you very much, Background Pony #1F36 :)