When you find something you can’t say, what do you do with it? My advice is, don’t say it. Or at least, pick your battles.

Suppose in the future there is a movement to ban the color yellow. Proposals to paint anything yellow are denounced as “yellowist”, as is anyone suspected of liking the color. People who like orange are tolerated but viewed with suspicion. Suppose you realize there is nothing wrong with yellow. If you go around saying this, you’ll be denounced as a yellowist too, and you’ll find yourself having a lot of arguments with anti-yellowists. If your aim in life is to rehabilitate the color yellow, that may be what you want. But if you’re mostly interested in other questions, being labelled as a yellowist will just be a distraction. Argue with idiots, and you become an idiot.

The most important thing is to be able to think what you want, not to say what you want. And if you feel you have to say everything you think, it may inhibit you from thinking improper thoughts. I think it’s better to follow the opposite policy. Draw a sharp line between your thoughts and your speech. Inside your head, anything is allowed. Within my head I make a point of encouraging the most outrageous thoughts I can imagine. But, as in a secret society, nothing that happens within the building should be told to outsiders. The first rule of Fight Club is, you do not talk about Fight Club.

When Milton was going to visit Italy in the 1630s, Sir Henry Wootton, who had been ambassador to Venice, told him his motto should be “i pensieri stretti & il viso sciolto.” Closed thoughts and an open face. Smile at everyone, and don’t tell them what you’re thinking. This was wise advice. Milton was an argumentative fellow, and the Inquisition was a bit restive at that time. But I think the difference between Milton’s situation and ours is only a matter of degree. Every era has its heresies, and if you don’t get imprisoned for them you will at least get in enough trouble that it becomes a complete distraction.

I admit it seems cowardly to keep quiet. When I read about the harassment to which the Scientologists subject their critics [12], or that pro-Israel groups are “compiling dossiers” on those who speak out against Israeli human rights abuses [13], or about people being sued for violating the DMCA [14], part of me wants to say, “All right, you bastards, bring it on.” The problem is, there are so many things you can’t say. If you said them all you’d have no time left for your real work. You’d have to turn into Noam Chomsky. [15]

The trouble with keeping your thoughts secret, though, is that you lose the advantages of discussion. Talking about an idea leads to more ideas. So the optimal plan, if you can manage it, is to have a few trusted friends you can speak openly to. This is not just a way to develop ideas; it’s also a good rule of thumb for choosing friends. The people you can say heretical things to without getting jumped on are also the most interesting to know.