The phrase "fatal flow of idealism" suggests that an excessive or unchecked idealism can lead to negative consequences or even disaster. It implies that having overly optimistic or unrealistic beliefs about how things should be can blind a person to the realities of a situation, making it difficult to make sound decisions or take effective action. In this sense, the "fatal flow of idealism" may indicate that holding onto idealistic beliefs without considering practicality or consequences can be harmful in the long run.
