On a recent episode of Jeopardy!, the contestants had a difficult time with this clue in the category “Quoting Poets”:
This Dylan Thomas title is rhymed with “Though wise men at their end know dark is right”
The correct response was “Do not go gentle into that good night.” Both of the contestants who buzzed in, however, substituted the word “gently” for “gentle.”
Their confusion is understandable. English teachers have been telling people for centuries that adverbs modify verbs (or verb phrases) or adjectives. That is, they tell us HOW someone does something, e.g., how did the man shout? He shouted loudly.