The changes are profound and the differences are consequential. Nearly weightless though it is, the word printed on a page is a thing. The configuration of impulses on a screen is not–it is a manifestation, an indeterminate entity both particle and wave, an ectoplasmic arrival and departure. The former occupies a position in space–on a page, in a book–and is verifiably there. The latter, once dematerialized, digitalized back into storage, into memory, cannot be said to exist in quite the same way. It has potential, not actual, locus. (Purists would insist that the coded bit, too, exists and can be found, but its location is not evident to the unassisted and uninstructed senses.) And although one could argue that the word, the passage, is present in the software memory as surely as it sits on page x, the fact is that we register a profound difference. One is outside and visible, the other "inside" and invisible.
-- Sven Birkerts, The Gutenberg Elegies