Why seven?

Why is the number seven so popular? Why seven habits of highly effective people? Seven spiritual laws of success? Seven pillars of health? Etc.?

I once read a good explanation of the popularity of the number seven in self-helpy book titles, but I can’t remember where, and it’s driving me crazy.

In trying to track this down, I’ve found what I gather is a widely known psychology paper by George A. Miller, from 1956, called “The Magical Number Seven, Plus or Minus Two: Some Limits on our Capacity for Processing Information.” (Wikipedia summary here.) It’s interesting, and it might partly underlie whatever it was I read, but my (possibly faulty) memory is that there was some more contemporary, market-linked, explanation — as in, sales figures showing books with “seven” in the title flat-out sell better. But I’m not certain. I could be totally wrong about that.

I do remember that back when I worked as an editor for personal finance magazines, cover lines like “Seven Stocks to Buy Now” supposedly sold better than “Six” or “Eight” stocks to etc.

I also came across this discussion of seven’s supposed lucky-ness, and where that might come from — the seven-day creation story, various other examples of religious and/or numeralogical seven-specialness. All interesting, but I have a nagging feeling that none of this is quite what I read earlier, and there’s something less esoteric out there, somewhere, on the subject of why seven might resonate with, say, book consumers.

If you have any thoughts, please let me know, below or at murketing AT robwalker DOT net. I will thank you seven times. Okay, once.