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This responsiveness had nothing to do with that flabby impressionability which is dignified under the name of the “creative temperament.”
— F. Scott Fitzgerald • The Great Gatsby

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The passage distinguishes responsiveness from impressionability and objects to dressing the latter up as a creative temperament. The word 'flabby' makes the criticism deliberately unflattering. The contrast suggests that sensitivity should not be confused with being easily swayed, even when a flattering artistic label is available.
Context reviewed