From Forbes:
More than half of total return from large capitalization U.S. stocks since 1926 has come from dividends, which provide a steady flow of cash that can be reinvested in more shares of stock. Using a company-sponsored direct investment (or dividend reinvestment) plan, dividends are automatically used to purchase more shares (and fractions) so that every penny of the payout is used to create a growing stake in the underlying company.