What is the Princeton pen ceremony?

It is a fiction created for the movie "A Beautiful Mind." Professors of all subjects have historically depended upon pens and ink to communicate their wisdom to others and to commemorate their individual contributions to the world. Surrendering one's pen is a symbol that the giver believes his own wisdom and contributions pale in comparison to the person receiving the pen. It is a symbolic homage, like laying down their sWords before their intellectual superior.