Ong, in Orality and Literacy, notes how print is a closed medium:
The printed text is supposed to represent the words of an author in definitive or ‘final’ form. For print is comfortable only with finality. Once a letterpress forme is closed, locked up, or a photolithographic plate is made, and the sheet printed, the text does not accommodate changes (erasures, insertions) so readily as do written texts. (pg. 130)
Ong also marks print as an important development in acquiring our sense of privacy, as reading, which previously was a social activity, became silent, an individualistic practice. Print encouraged the “private ownership of words,” and resentment at plagiarism developed as a result.
In contrast with print, the blog is an open medium. It is, most importantly, never final — the reverse chronology of the blog’s posts creates an implicit open-ended form. A post itself can also be edited, and some bloggers, Glenn Greenwald of Salon comes to mind, frequently use an “Update:” to continually add new information to their pages.
The blog, interestingly, parallels in many aspects what Ong and McLuhan call “manuscript culture,” that period of time after the invention of the alphabet, after writing, but before print fully restructured our consciousness:
…manuscripts, with their glosses or marginal comments (which often got worked into the text in subsequent copies) were in dialogue with the world outside their own borders. They remained closer to the give-and-take of oral expression. The readers of manuscripts are less closed off from the author, less absent, than are the readers of those writing for print.
Here the corollary to the blogosphere is evident: comments, a close relationship between “author” and “reader,” the give-and-take of discourse.
Unlike the closed world of print, the blog is open, confounding our previous conceptions of public and private, always subject to edit, always waiting for the next, new post.