"Light travels faster than sound. This is why some people appear bright until you hear them speak"

This quote by Alan Dundes is a funny method of stating that looks can be deceiving. It is suggesting that someone might seem smart or well-informed, however when they speak, their real absence of knowledge or understanding is exposed. The quote is making a comparison between light and noise, keeping in mind that light journeys faster than noise. This is a metaphor for how quickly someone's real character can be exposed. It is a tip to not judge a book by its cover and to make the effort to learn more about someone before making assumptions about them. Ultimately, this quote is a suggestion to be conscious of our own words and actions, as they can quickly reveal our real character.