Copying by hand

A couple weeks ago, I noticed in a BoingBoing post the following quote:

Before literacy, we were mere listeners. We heard stories read to us as a group. After the printing press, we were elevating to individuals, each with our own, acknowledged perspective on what we read.

I made a comment (as "hilbertastronaut"), and I feel like expanding on
it a bit more.

The writer argues that the printing press elevated us (Westerners,
perhaps?) from mere listeners to individuals with opinions. If
anything, the opposite might be true. Back when the only way to
propagate information was to copy it by hand, it was standard practice
to add commentary to the margins of the document. This could include
clarifications or even personal reflections. One sees this in Western
monastic manuscripts as well as Chinese brush paintings (where
standard practice was to indicate receipt of the painting by marking
it with one's personal stamp, and then perhaps write one's thoughts on
the piece in the margin). In contrast, the printing press (and the
Reformation in some sense) gave people the idea of a book as an
official, received text. Written comments have a lesser status than
the printed text. For example, if one buys a used textbook at a
college bookstore, one generally hopes that it hasn't been written on
much. Before the printing press, the commentary could often be equally
or more valuable than the main text itself.

Copying other kinds of information by hand besides text also has
the same effect. For example, when J. S. Bach copied Italian
concerti, he added inner voices and ornamentation, making the concerti
into pieces universally recognized as his own compositions (and
arguably more interesting than the originals!). Bach treated copying
both as an end (to get his hands on other people's music), and as a
means (to improve his compositional skills). Even today, mathematics
teachers consider copying out and working through proofs an important
part of learning mathematics. This is because mathematics, like music
composition, is not about memorization of facts but about developing
one's creative problem-solving ability according to a combination of
rules and aesthetic principles. Copying a proof and understanding
each step is a guided re-creation of the original author's work.
Furthermore, creative mathematical thinkers in this process of
re-creation usually have new things to say, like clarifications or
generalizations, which they "write in the margins" and use in their
research -- just like Bach wrote inner voices and ornamentations "in
the margins" to produce new compositions.

My sophomore high school English teacher handed out red pens on
the first day of class, and exhorted us, even required us to
write in our books with them. At the time, it seemed ridiculous to
ruin books which could be reused for the next class. Pencil
annotations could at least be erased. Now I understand that using a
red pen elevates the status of the handwritten text, to be more
visible and more permanent even than the printed text. It makes the
reader's commentary just as valuable, if not more so, than the
original document. Whether my commentary really was more valuable
than what I read at the time is doubtful, but at least the long-term
lesson of the value of "manual" commentary stuck in my head.