Knowledge is power only if man knows what facts not to bother with.

The remark qualifies the familiar maxim “knowledge is power” by stressing selection and judgment. Mere accumulation of information does not automatically confer agency; power comes from knowing what is relevant, reliable, and actionable—and from ignoring distracting, trivial, or misleading “facts.” Implicitly, Lynd is pointing to the limits of human attention and the social costs of information overload: time spent chasing every datum can paralyze decision-making and obscure larger patterns. The line also hints at a pragmatic, even democratic view of intelligence: wisdom is not encyclopedic recall but the ability to sift, prioritize, and focus on what matters for a given purpose.