This quote, from his mentor Benjamin Graham, captures an important point: day-to-day prices reflect investor sentiment, while long-term returns reflect actual business performance.

Rather than short-term market moves (the "voting"), Buffett looks at long-term fundamentals, like a firm’s revenues and profits (the "weighing"). When the dot-com bubble sent valuations soaring, he stayed away from speculation – by 2002, when market euphoria gave way to economic reality, Buffett's focus on value proved prescient.