A Contemprary Commonplace Book

It recently struck me that a blog resembles the commonplace books people used to keep, in which they would record any events or quotations that struck them as interesting, and any thoughts that came into their heads, occasionally adding little illustrations.

The principal difference is that blogs are usually public, or at least usually accessible by a moderately large audience, whereas a commonplace book would often be read only by the author and possibly the author's descendants, but there's still a great similarity.