Anthony Kendall is one of my favorite bloggers, though he seems to be busy with other things these days and posts only occasionally. He wrote an interesting post a couple of weeks ago suggesting that the role of the boat in the expansion of human civilization throughout the world is a better analogy for private space development than the often used analogy of aviation development in the early 20th century.
The solar system is the new ocean, and while we are still splashing around in the shallows of low Earth orbit (a few Moon walkers and robot surrogates notwithstanding), we will build bigger and better boats to explore and eventually live on the more distant shores. Note that this corny paraphrasing of the analogy is mine, not Anthony's!
The picture is just one that I happen to like from my France trip - but it has a few boats in it.