The Sociological Imagination provoked hostile reaction when it appeared for its hard-hitting attack on how sociology was practiced, and on several leading sociologists. A fierce critic of both modern capitalism and Soviet-style authoritarianism, Mills argued that sociologists failed to consider how people's problems are connected to the structures of their society criticizing two leading tendencies of sociology: focusing only on research data while excluding larger issues, and concentrating on solving abstract theoretical problems with no regard for the real problems people face in their lives. Mills' book is now considered a key explanation of the fundamental mission of sociology.