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 shared 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 on price gyrations, yet dividends have historically accounted for more than half of total returns.

Reinvest those dividends, and it's even greater. Take H. J. Heinz (NYSE: HNZ) for example. Since the late 1960s, Heinz's share price has increased 5,900%. But add in reinvested dividends, and total returns jump to 23,900%:

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

There's no ambiguity here: Over time, Heinz's share appreciation alone has paled in importance to the power of its reinvested dividends. The results are similar for other food companies such as Campbell's Soup (NYSE: CPB) and Kellogg (NYSE: K). Reinvested dividends skew both companies' total long-term 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 Heinz's dividends look? The company has paid a dividend every year since 1911, growing its payout by 7.4% per year over the past quarter-century. At 3.5%, its yield is well above the market average. Over the past five years, dividends have used up an average of 53% of free cash flow, giving plenty of room for earnings to fall before threatening a dividend cut. "Our priorities remain largely unchanged," said CFO Arthur Winkleblack on a recent conference call. "First, our target is to protect and grow our dividend." Smart choice.

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.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.