In this book on eleven-dimensional space-time, Brian Greene proves himself to be truly exceptional in at least three of those dimensions:  by his thorough comprehension of the origins and direction of theoretical physics  up through the emergence of superstring theory, by his monumental  contributions to that theory in identifying its components and extending  its reach, and, thirdly, in explaining this subject in a way that allows  the "layman" to gain an appreciation and intuitive understanding of  it.<br>By way of explaining the use of the term "layman," let me point out  that this book is not light reading.  I don't believe it can be read by  those without at least some exposure to college level physics.  I am a  former high school physics teacher, and I had to really stretch to  understand Dr. Greene's explanations.  Nevertheless, considering the  mathematical and physical complexity of the subject matter, Dr. Greene has  done a splendid and remarkable job of explaining the subject at a  conceptual, nonmathematical level. Anyone with a physics background through  the level of an introductory course in modern physics will find Dr.  Greene's treatise accessible.  It brings the reader closer to the current  state of research in the rapidly moving field of superstring theory than  books written even two years ago.<br>  The book requires work, but it was  a labor of love.  This book is beautifully and artfully written and was a  joy to read.  I recommend it highly to anyone with the modest physics  background described above who enjoys exploring theoretical physics and  cosmology at a level approximating that of Scientific American.