Warren Buffett on how to value a business

What counts... is intrinsic value - the figure indicating what all of our constituent businesses are rationally worth.  With perfect foresight, this number can be calculated by taking all future cash flows of a business - in and out - and discounting them at prevailing interest rates.  So valued, all businesses, from manufacturers of buggy whips to operators of cellular phones, become economic equals.

~ Warren Buffett, Berkshire Hathaway 1989 Annual Report, March 2, 1990