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 more than half of total returns.

Reinvest those dividends, and the gains get even greater. Take Duke Energy (NYSE: DUK), for example. Since the late 1960s, the company's share price has increased 203%. But add in reinvested dividends, and total returns jump to 4,600%

Dukdiv

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

There's no ambiguity here: Over time, Duke's share appreciation alone has paled in importance to the power of its reinvested dividends. The results are similar for other utilities like Entergy (NYSE: ETR) and CenterPoint (NYSE: CNP); 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 Duke's dividends look? At 5.4%, its yield is far above the market average. The company has paid a dividend every year for the past 84 years -- truly a remarkable track record. Energy prices do a number on utility companies' cash flow, but Duke has weathered the storm well. "Our annual dividend increases continued uninterrupted during a severe economic recession that forced other companies to slash or even eliminate their dividends," said CEO James Rogers on a recent conference call. "Duke Energy's dividend remains a key cornerstone of the company's value proposition."

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.