This is a question I spent a little time digging into today. Leaving aside weapons and artist's tools (though I'm not sure that the now-common "the sword is an extension of the swordsman" rhetoric isn't actually very modern), I want to know, what machine did users first describe as an extension of their bodies? (You'll have to read the book to see how this fits with contemplative computing.)
I think the answer is: the bicycle. The first example I can find is from 1869 issue of All the Year Round:
It [the bicycle] is worse than useless until animated by the guiding intelligence of which it becomes the servant and a part. Without its rider it consists merely of a couple of wheels and a crank or two, and looks like a section of broken cab as it lies helplessly on the ground. But it increases your sense of personal volition the instant you are on its back. It is not so much an instrument you use, as an auxiliary you employ. It becomes part of yourself.
I also found something from 1909-- by which time the automobile and motorcycle were also being described using similar language.
The great charm of it all is indescribable. You and your wheel are one. The machine is an extension of yourself. On any other vehicle you are freight. Here you are moving by your own will and strength. You feel that your joy must be akin to that of the eagle's flight, the very poetry of motion. You forget all about destination, rate of speed, extension of muscle; and you swing along exulting in the flight itself.
If anyone knows of examples of other technologies (steam travel? possibly conductors or ship's captains felt that way, but they were a small elite), let me know.