Belatedly comes the realization that `personal computing' does not imply `isolated computing'--if anything just the reverse, compared to the dedicated-function mainframes of old--but the genie is out of the bottle. Now we find ourselves in the odd situation of having myriads of these so-called personal computers connecting to the internet with essentially no systematic defenses, no immune system, and precious little sense of self. The scale of it is quite staggering, with the internet growing from thousands to tens of millions of hosts just in the last decade. Epidemic waves of infections flash through the networked population faster and farther than any natural pathogen--constrained to transmission vectors involving slow-poke matter--ever did, even as the exploding size and thus value of the global network makes remaining unconnected increasingly untenable for many purposes.
It is no wonder that the computer security industry is booming. Widely underappreciated is the fact that current commercial security systems, constrained to deal with the deployed base of hardware and software, are for the most part exactly as ad hoc, awkward, and unreliable as a plastic bubble is as substitute for an immune system--it works better than nothing, but surely you wouldn't trust your life to it if there was a more integrated and robust alternative.