Great phrase. The bane of censors and the christian right.
All knowledge is good knowledge. That's why we are vaugely intrigued by the extreme and disgusting. Knowing is always better than ignorance, even if it's something you may not want to hear.
Rather than restricting information for moral reasons, todays censorship on things like Napster and DeCss makes it seem like this phrase may be modified by large corporations to some knowledge is too profitable to bear.