The defining element of the desktop GUI is the icon, which, although it often has a name, is above all a picture that performs or receives an action. These actions give the icon its meaning. As elements in a true picture writing, icons do note merely remind the user of documents and programs, but function as documents and programs. Reorganizing files and activating programs is writing, just as putting alphabetic characters in a row is writing. Rather like the religious relics after which they are named, computer icons are energy units that focus the operative power of the machine into visible and manipulable symbols. Computer icons also remind us of the cultural functions of Hebrew letters in the Cabala or of alchemical and other signs invoked by such Renaissance magi as Giordano Bruno. Magic letters and signs were often objects of meditation, as they were in the logical diagrams of the medieval Raymond Llul, and they were also believed to have operational powers. As functioning representations in computer writing, electronic icons realize what magic signs in the past could only suggest.
Jay David Bolter