The premise of Inventing the Medium is that computation has created a new medium of representation. How do we know when we have discovered a new medium? One answer might be that we know it by the combination of terror and delight that we experience as pioneering practitioners explore the new affordances for human expression.
For cinema there is mythic moment associated with the birth of film, the Lumière Brothers 1895 showing of a film about the everyday occurance of the arrival of a train.
Janet H. Murray 