Prospero

Thou shalt be as free

As mountain winds: but then exactly do

All points of my command.

(The Tempest 1.2)

About the Name
Prospero is a character in Shakespeare's The Tempest. In the play, Prospero, the former Duke of Milan, has been been set adrift with his young daughter Miranda by his treacherous brother and lands on a magical island. Prospero uses the island to learn magic. Among Prospero's final acts on the island is to set Ariel, who was imprisoned in a tree, free. Ariel can be seen only by Prospero and carries out tasks for her master.

In a similar vein, the program Prospero uses a bit of programming "magic" to set documents free - from paper (wood pulp). The library patron can decide to keep the document "free" or to imprison it back on paper.