I took my first investing class as a teenager, and one moment stands out in my memory. A fellow student asked the instructor, a stockbroker, about dividends.

"Dividends?" he asked. "I'm trying to make my clients wealthy. You don't do that waiting for tiny checks in the mailbox every quarter."

Even then, I had enough horse sense to know he was wrong. Paying attention to dividends is exactly how you become wealthy over time.

Wharton professor Jeremy Siegel made a wonderful discovery in his book The Future for Investors. The greatest long-term returns typically don't come from the most innovative companies, or even companies with the highest earnings growth. They come from companies that happen to crank out dividends year after year. Simply put, since the 1950s, "the portfolios with higher dividend yields offered investors higher returns."

Market commentary regularly centers around price gyrations, yet dividends have historically accounted for about half of total returns.

Take Air Products & Chemicals (NYSE: APD), for example. Since the late 1960s, the company's share price has increased 7,800%. But add in reinvested dividends, and total returns jump to over 16,600%:

Apddiv

Source: Capital IQ, a division of Standard & Poor's. 

There's no ambiguity here: Over time, Air Products & Chemicals' share appreciation alone has paled in importance to the power of its reinvested dividends. The results are similar for others in the chemical space such as Dow Chemical (NYSE: DOW) and Ashland (NYSE: ASH); reinvested dividends skew both companies' total returns dramatically higher. If you're a long-term shareholder, don't worry about daily share wobbles. Devote your attention to those dividend payouts and your commitment to reinvest them.

And how do Air Products & Chemicals' dividends look? At 2.9%, its yield is above the market average. The company has paid dividends every year since 1954, increasing that payout every year for the past 29 years -- a performance that has earned it a coveted spot on S&P's Dividend Aristocrats Index. That track record bodes well for a future of delivering above-average returns.

To earn the greatest returns, get your priorities straight. What the market does is less important than what your company earns. What your company earns is less important than how much it pays out in dividends. And what it pays out in dividends is less important than whether you reinvest those dividends.

Fool contributor Morgan Housel doesn't own shares in any of the companies mentioned in this article. Follow him on Twitter @TMFHousel. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.