For many, the question is about the next gallon of gas. Petrol cost $1.46 per gallon some 20 years ago, adjusted for inflation. I guess that means it is rich now, at about $2.70. Gas in 1931 was about the same as in 2015, around $2.76.

One view of a gallon of gasoline. My colleague John Tucker sold his Hummer when the price of gas reached $4.00 per gallon in 2008.

How are commodities doing? I find great disagreement and—too often—faulty analysis stemming from cluelessness about the long view. Here is a short-term snapshot, ready made for media panic:
We're all going to die. The Bloomberg Commodity Index is off a cliff, I say!
The truth is that you can find individual "commodity gloom" at any given moment, though the chart shows an index, which smooths things out a bit. A longer view adds value. Here is the same blended index of 22 members over 24 years:

The same basic chart, but we are not going to die. Instead, it is vuja de. We have recently collapsed to "new lows" that take us back to late 1995.
Yet that is still how amateurs (all right, informed amateurs) look at the commodity market.

Here is how professionals—particularly pros with a grounding in economics—look at commodities:

I have used the Continuous Commodity Index, based on the "old" Commodity Research Bureau (CRB) Index that was devised in 1957 by the New York Board of Trade.

That's the chart adults use as the foundation for shorter-term analysis. If you don't have this chart in long-term memory, ugliness happens in the short-term speculative space. This six-decade chart is adjusted for inflation. The real price of commodities has declined some 60 percent over the half-century (the red trend line). Commodity pros start every analysis knowing that the structural trend in commodities is south. It is normal for commodities to depreciate.

Other than the early petro 70's and recent China-driven joy, the trend is not your inflation-adjusted friend.

The yellow trend line offers a rough answer to the question: What would the trend be if we looked only at the trend moments and tried to forget the two bouts of boom? I grabbed the ~1982-2002 regression. It beautifully extrapolates back to the trend of ~1956-1971. More interesting, I extrapolate the regression forward, beyond the recent inflation-adjusted advance, into the foggy future. It goes without saying that a return to trend (red) or to an approximate no-boom trend (yellow, the lower right) is something that most are not considering.

Why do commodities trend south? There is a debatable set of answers, but there is overwhelming agreement that "technological progress" is the arch-reason. Over the eons, centuries, and last two quarters, we have generated the gross engineering to do commodities better.  

So how are commodities doing? Commodities are beyond enticing, and offer a great way to turn $423,000 into $178,235.74. Just try to keep in mind the brute force of the trend.