I thought I had as good a grasp of our current understanding of the universe as could be reasonably expected from a layperson, but Greene lays out not only the foundations of superstring theory, general relativity and quantum mechanics, but cosmology and physics itself in such a clear, lucid manner that certain concepts which had previously eluded me (like curled up extra dimensions) are now within grasp (as well as several that had never even occurred to me).