Among Cramer's favorite long-term themes is aerospace. Here are 4 reasons why:
1. "First, aerospace is about progress, and if you're looking for a historical theme that's unstoppable, it doesn't get any better than progress," Cramer said.
In the case of aerospace, Cramer thinks as the emerging world progresses, more people around the world will enter the middle class. In turn, more people should travel, and more travel should drive demand for planes.
2. "Second, with fuel prices relatively high, the airlines can't afford to not to upgrade their planes," Cramer added. That is, the cost of fuel has become such a substantial part of running an airline, the major carriers need to buy the newer and more fuel efficient planes to turn a profit.
3. "Third, you have to keep up with the Jones's, that is the new creature comforts of planes," Cramer said. Again, airlines need to buy new planes simply to compete with rivals.
4. "Finally, nothing last forever," Cramer said. That is, carriers must order planes today for aircraft needed years from now, because of the substantial backlog and time needed to build a plane.
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Because of the all reasons outlined above, Cramer believes demand for new planes will grow stronger and more robust for many years to come.
Therefore, when the market declines sharply as it has in recent days, Cramer believes investors should make a shopping list, and buy stocks that allow you to invest in this long-term theme.
"Of course there's Boeing," Cramer said. "I think Boeing is terrific. But there's more than Boeing." Cramer also suggested looking at United Technologies and Honeywell, the makers of engines and cockpits. And he recommended putting Precision Castparts on the radar too.
There are other plays in the space, but those mentioned above are Cramer's favorites. "No need to overthink this," he said.
