Reflections usually take time to mature but the first one is why blog in the first place.
Still working this one out – a classical education could lead you to a narcissistic explanation …. but equally (and perhaps just as likely) to the view that writing, like carving, is a way of cutting to the important and in so doing creating a personal sense of order in a world of apparently increasing complexity. The scale of communication, memes, and inter-generational preservation of knowledge through libraries is what sets Homo sapiens (? the specific epithet ) apart from other genomes, so is blogging just part of the evolutionary process ?
Others have pondered too –
http://www.becomingminimalist.com/15-reasons-i-think-you-should-blog/