We know that the markets are cyclical. They go up-down, up-down.

Listening to the news, you’d never know this. When gas hit $4 a gallon several years ago, headlines said it would go to $7 or more—but instead of doubling, prices fell by half. This shouldn’t be a surprise, especially for those of us old enough to remember the oil crisis of the 1970s. The glut of oil we see today is really just a symptom of the shortage a few years back.

When gas is scarce and prices are high, nobody wants to use any. People drive less, take fewer trips, and buy more efficient cars. At the same time, oil producers start falling over themselves to drill everything in sight. Eventually, the high prices cause demand to shrink and supply to grow.

We know what comes next: oversupply and plummeting prices. Now producers are spending too much money pumping cheap oil and have to close down plants. At the same time, people get used to cheap gas and start burning it freely. Truck and SUV sales go through the roof and people drive more miles. We think we know how this one ends, too.

Every glut plants the seeds of the next shortage, and every shortage plants the seeds of the next glut. We can see this happening in real time with oil and other natural resources such as iron and copper. It holds just as true with every other market in every other age—cattle, corn, and cars, smartphones and other gadgets, even abstract “goods” like movies and music.

Timing is nearly impossible to predict, and investments can be volatile and difficult to own. But by understanding how the process works, patient investors may profit. Today’s bust may be tomorrow’s boom.