The British Library currently have John Milton's commonplace book on display. I found the experience of looking at it quite remarkable. Commonplace books are allowably messy, whilst serving an important function in the development and management of an individual's mind. 'Commonplacing' was something promoted in Universities until the early part of this century. The similarities to blogging are striking: but there is an important difference.
Commonplace books were not usually intended to be public (apart of a few examples in this century (Auden, for example)): they were testimony of a private conversation the author would have with themselves; the physical marks on the page serving as an aide-mémoire of the development of mind.
I have to admit that my blog is very much an 'aide-mémoire': I see how my thinking develops, what happens in the world, what caused certain ideas to arise, what then takes their place, what I have read, etc. My practice with my blog is certainly similar I think to the practice of commonplacing.
But blogging is public. It's a game that is played for raising one's profile as much as developing one's mind. The development of mind has become something of a 'performance art' in a way that would have seemed very strange to Bacon or Milton. Their public profile would have rested on their published works and their political standing. The process of their mental development, which commonplacing formed a part, was something that served the purpose of their publications and politcal activity.
What seems to have happened is that the processes of mental development are now seen as significant and worthy of public recognition. This may have something to do with education and the need to model the practice of thinking as much as to be an 'expert'. But should all acts relating to mental development be public?
The problem is that the technologies we possess work with searchable texts which can be recalled instantly and (potentially) used in a political way to manipulate the reputations of others at distant moments in the future. I think those who remain resistant to blogging fear this, and in a way, rightly so.
There remains a need for human beings to articulate their innermost thoughts in ways that only they can understand. It may be that the artefacts produced through such an articulation are indeed public, but that the intentions of the maker remain hidden behind their cyphers. Technology gives us fantastically powerful ways of organising things (I could never have been organised enough to keep a proper commonplace book - I would have lost it!). But I have needed my cyphers. Indeed, I would not have blogged in the first place if I hadn't found a way of making them.