$1,000 Google? Sure, but Why Bother?

And it would send net income to $70 billion -- or 75% more than Exxon Mobil is managing to make today.

Possible? Sure. Likely? We'll see.

Yet this is what has to happen if Google is going to return 20% a year from these levels.

And less heroic assumptions take their toll on the numbers. Imagine the earnings grow by a more modest 20% a year over this period. That's still a pretty remarkable compound growth rate for a decade. Imagine, furthermore, that the stock ends up in 10 years' time on 18 times forecast earnings, in line with recent market averages.

In that scenario, your shares will have only made you about 9% a year.

Nine percent.

Sure, it's a decent return. Risk-adjusted? Maybe not. If long-term earnings growth is just 15% a year, the shares are only going to make 6%.

Everything profitable has a value. And that value, alas, is always a finite number.

Meanwhile, the bulls are in charge and animal spirits are roaring. So who dares talk in terms of limits?

Next week: "Google $2,000!"

(Do I really mean $2,000 factorial? Maybe. Why not?)