From that most holy wave I now returned to Beatrice; remade, as new trees are renewed when they bring forth new boughs, I was pure and prepared to climb unto the stars. (Purg. XXXIII, 142-145)
Dante’s education is complete. After his horrific lessons in Hell and his penance in Purgatory, the waters of the Lethe river wash his mind completely clean by the and he is ready for Heaven. The mundane message to take away seems to be that a good education can, after long, hard hours, provide a student access to places previously locked to him.