Great quote! (Talk about be smacked with your own hidden assumptions...)
Got a link to the surrounding text?
On Google Books (limited online availability, but search for "habitually").
If you Google the title, you'll find the full text on a Brazilian website; whether legally or not I don't know.
This is our monthly thread for collecting these little gems and pearls of wisdom, rationality-related quotes you've seen recently, or had stored in your quotesfile for ages, and which might be handy to link to in one of our discussions.