Like cuttlefish we conceal ourselves, we darken the atmosphere in which we move; we are not transparent. I pine for one to whom I can speak my first thoughts; thoughts which represent me truly, which are no better and no worse than I; thoughts which have the bloom on them, which alone can be sacred and divine. Our sin and shame prevent our expressing even the innocent thoughts we have. I know of no one to whom I can be transparent instinctively. I live the life of the cuttlefish; another appears, and the element in which I move is tinged and I am concealed.
(Henry David Thoreau,
Which, in addition to being well put, has as much to do with why some people choose to blog their personal lives anonymously as anything does.