Over the past hundred years, humanity has made spectacular progress in acquiring knowledge about the universe, the past, and itself.

The history of the great pre-classical civilizations and the history of human evolution have been explored and mapped in detail. These advances have been enormous, exciting, and consequential.

Yet a remarkable fact accompanies these developments: Whereas it was once believed that every advance in knowledge reduces our ignorance, recent giant leaps have shown us how little we actually know.

This inquiry thus creates a paradox: increasing knowledge heightens our ignorance. So what do we know? And what do we now know that we do not know?

What have we learned about the nature of research itself—the barriers and difficulties that must be overcome or taken into account? What are the limits of knowledge, and how can we transcend them?