It's said that if a frog is placed in boiling water, it will jump out and stay safe, but if it is placed in cold water that is slowly heated, it will not perceive the danger and will be boiled to death. The story is a metaphor for the inability of people to perceive and react to significant changes in their environment. Whether true or not its a useful reminder that we need to stay alert to changing customer needs, competitor innovations and your organisations morale and culture.