His gestures grew more animated. "See, information is written on memory chips and hard drives by a beam of light, and read in the same manner. Individual pulses within the beam, as well as the light wave’s pattern of crests and troughs, are all part of the information-carrying code. If a creature made of light suddenly surged through a data storage device, it would completely scramble the code that had been written previously. There’d be a whole new pattern laid down, none of it coherent. And that’s what makes this spirit so perfect as a virus. There’s no way to stop it from corrupting your data. Even if you installed a passcode system, any word or image you use is encoded as light. All the spirit would have to do is reconfigure itself to emulate the passcode, write-enable the datastore, and slide right in. Only a hardwired lock could stop it—and that involves completely locking the system away from the Matrix. It just isn’t economically feasible to do that.