I understand what you are saying about technology a hundred years ago not having a big effect on people's lives. As many posters have said, this is erroneous, but this could be a matter of semantics more than a conceptual error. Back in the good ol' days a far greater percentage of the general populace understood the workings of their basic implements, as there were few extremely complex examples outside the realm of academia that had far reaching effects.
Obviously the railroads and firearms industries are the best examples of technologies being implemented by massive numbers of the general public without an acute understanding of the minutiae involved. Yet even the simpleton of the day had an understanding of how to utilize these tools, just not how to produce them.
The concept David is attempting to elucidate is one more subtle. Correct me if I am wrong, but this seems to be a matter of our world shifting more and more towards a division of labor society. One of the last men to be a true expert in every field of academia was Gottfried Wilhelm Liebniz, and he was an intrepid genious of the first class. The world since his time has become more complex on an astronomical scale and at a staggering pace. It is simply impossible for anyone to be able to learn, in intricate detail, the dynamics of our modern world.
The concept does not end here, it only shows how, as the world becomes more intricate, we will find ourselves more and more detached from our own sustaining technologies.
The psychological effect will be one of universal bewilderment. Except for those who sink into their own area of expertise, and maintain only a working knowledge of those things whoxh are required for our mutual survival.

I want to keep thinking and writing, but responsibilities pull me away

Cambraceres