"People are mostly sane enough, of course, in the affairs of common life: the getting of food, shelter, and so on. But the moment they attempt any depth or generality of thought, they go mad almost infallibly. The vast majority, of course, adopt the local religious madness, as naturally as they adopt the local dress. But the more powerful minds will, equally infallibly, fall into the worship of some intelligent and dangerous lunatic, such as Plato, or Augustine, or Comte, or Hegel, or Marx."
-- David Stove, What Is Wrong With Our Thoughts
(Since there didn't seem to be one for this month, and I just ran across a nice quote.)
A monthly thread for posting any interesting rationality-related quotes you've seen recently on the Internet, or had stored in your quotesfile for ages.