A new challenge for science: The world is complex, and so should our concepts of it be. Many disciplines in the humanities and social sciences have long adhered to this maxim. However, the natural sciences have traditionally sought simple, universal, and timeless laws. They aimed to explain the "buzzing confusion" that untrained senses present to the mind. But this endeavor has failed. Sandra Mitchell demonstrates that the complexity of the living world compels us to radically revise our models of thought and seek a more adequate epistemology. To this end, system theory has provided guidelines that have been specified by complexity theory in recent years. Complex systems - like the world we live in - are characterized by this complexity.