Leaving spaces between words: reinvented during Charlemagne's reform of writing, the leaving of spaces between words enabled many readers to switch from reading aloud (which was the common way to read during the Middle Ages) to reading silently. Franc, c. 800CE.
What I find fascinating about this fact is the kind of mental space that silent reading allows. Pragmatists, like Wilfred Sellars and impressed by Wittgenstein's argument against private languages, have emphasized the need to see thinking as development from speaking, i.e. as the internalisation of a communicative function. This is opposed to a more classical view of speaking as derivative from thinking - as the expression of a thought that precedes the locutive performance.
The pragmatist approach subordinates theories of mind to theories of social practice. Minds are the kinds of things we have by virtue of our participation in a sophisticated social community.
Pragmatists regard traditional theories of mind, which take an individual's cognitive relation to a value-neutral world as primary, to be beginning with the wrong question. They see the development of the notion of an objective, mind-independent natural world in terms of its particular social function.
So far so good. Pragmatism works well as a criticism of traditional epistemology. However, I'd prefer to avoid a pragmatism that sees everything in terms of social values, because I think people are capable of disputing and interrupting social values in many ways. I also think that much of that resistance to social norms - which ultimately gives those values their normative significance - centres on the anomalous subject's embodiment.
Now, a full blown critique of (the strictest forms of) pragmatism would need to show that the development of the very social practices to which pragmatists appeal cannot be understood except via an account of corporeal embeddedness.
And this is where we come back to the spacing of words. What is the relationship between the spacing of words and the internalization of communication as thought? Charlemagne was responding to the capture of literacy by the priestly class, and proposed no less than a revolution in communication through the different corporeal stance toward a text. Charlemagne's reforms traded on the Gestalt properties of vision to break the connection between text and speech. These Gestalt properties cannot be understood in terms of social practices.
In the case of Charlemagne's reforms, it is the Gestalt character of the perceived world that acts as the hinge around which the reform of social convention occurs. Social change involves exploiting aspects of a presupposed embodied relation to a pre-social world (pre-social in the sense that the social conventions that determine the meaning of the text do not determine the limits of this relation as well).
It is through our bodies that social conventions get a grip, and it is through exploiting the ambiguity of embodiment - it's ability to escape being comprehensive controlled through its actual performances, because it maintains around it an aura of possible performance - that we can modify and affect the character of our social world.
So, our embodied perception of gestalts allows for thinking room between reading and speaking. Merleau-Ponty says that vision is thought within a field. Here the field (room) for thought is the space between words.