Motoko is supposed to represent the closest mankind has ever gotten to what is known as the machine singularity. When mankind is fully integrated with machine.
In computer terms, a ghost in the shell is when a computer program begins to write it's own code, nullifying the need for any programmer. This was believed by scientists as the first signs of a computer becoming self aware or artificial intelligence.
Only a few times have it's been seen when code has appeared out of no where. It was always thought it was programmed by a ghost.