"I shall not today attempt further to define the kinds of material but I know it when I see it"

This quote by Potter Stewart is frequently utilized to describe the difficulty of defining profanity. Stewart was a Supreme Court Justice who was charged with identifying what constituted profanity in the 1964 case Jacobellis v. Ohio. In his viewpoint, Stewart wrote that he could not specify profanity, but he knew it when he saw it. This quote has become a popular phrase to describe the problem of defining something that is subjective and tough to measure.

Stewart's quote is typically used to explain the trouble of defining something that is not easily defined. It is a reminder that there are some things that can not be easily specified, however can still be recognized. This quote is also a pointer that in some cases it is much better to rely on our own judgement and intuition when it pertains to making choices. We may not be able to define something, however we can still recognize it when we see it.