Monthly menstruation for decades on end is not the historical norm.

It has been the historical norm, the way that things have always been done.

Anyone who looked at historical norms would have concluded the market was cheap.

Religion also played a big role in politics a century ago, so we may well be returning to the historical norm.

Current deformation patterns at Yellowstone are well within historical norms.

Meanwhile, the average stock is selling at 31 times earnings, twice the historical norm.

Yet the average Nasdaq stock is still trading at 80 times earnings, far higher than the historical norm, he said.

In other words, by this measure, investors actually seem slightly more optimistic than the historical norm.

But it often takes six or seven years for returns to revert to their historical norms, he said.

Even now, he said, American share prices are too high, about double historical norms.