Those familiar with Marshall McLuhan will remember his view, and it was not his alone, that our technologies are fundamentally extensions of ourselves. And in McLuhan’s view, electric technologies were extensions of our nervous system. So, for example, In Understanding Media, McLuhan writes:
“With the arrival of electric technology, man extended, or set outside himself, a live model of the central nervous system itself.” (65)
“When information moves at the speed of signals in the central nervous system, man is confronted with the obsolescence of all earlier forms of acceleration, such as road and rail. What emerges is a total field of inclusive awareness.” (143)
“It is a principle aspect of the electric age that it establishes a global network that has much of the character of our central nervous system. Our central nervous system is not merely an electric network, but it constitutes a single unified field of experience.” (460-461)
Those familiar with McLuhan will also know not only that McLuhan was a Roman Catholic (recent essay on that score here), but that he was influenced by the thought of a relatively fringe Catholic paleontologist and theologian/philosopher, Teilhard de Chardin, who, in The Future of Man, spoke of technology creating “a nervous system for humanity … a single, organized, unbroken membrane over the earth … a stupendous thinking machine.”
As it turns out, McLuhan and de Chardin were trading in a metaphor/analogy that had even older roots. At the outset of his fascinating (if your into this sort of stuff) study Electrifying America, David E. Nye cites the following passage from Nathaniel Hawthorne’s The House of Seven Gables, in which the character Clifford exclaims,
“Then there is electricity, the demon, the angel, the mighty physical power, the all-pervading intelligence!” … “Is it a fact — or have i dreamt it — that, by means of electricity, the world of matter has become a great nerve, vibrating thousands of miles in a breathless point of time? Rather, the round globe is a vast head, a brain, instinct with intelligence! Or, shall we say, it is itself a thought, nothing but a thought, and no longer the substance which we deemed it!”
Hawthorne’s novel, in case you’re wondering, dates from 1851.
L.M. Sacasas 
Hawthorne lived, of course, during a time when the American version of Romanticism still pervaded intellectual thought; and he was part of the transcendental movement, so his environment was rich in thought that in part reacted against rational and scientific thought per se about nature, the time of Emerson and others. Hawthorne’s application, as above, is interesting, as many transcendentalists saw their connection to nature in individualistic ways, whereas his seems to be a more universal one that connects all parts of nature into one, if I understand correctly. He was privileged to be a part of a large movement which continues today in areas such as Process Theology and the ongoing influence of Teilhard, fringy or not! and quite a bit of New Age mysticism.
Indeed, and it is the reaction to “rational and scientific thought” (among other things) that makes them a source of enduring insight as a kind of counterpoint to prevailing moods and narratives.
Mostly, I was struck by how early this metaphor appears, predating electrification even. And for the record, I wouldn’t want to suggest a direct influence on McLuhan and Teilhard de Chardin, unless of course someone out there could point me to the link!