Richard P Gabriel was one of the six persons responsible for the CLOS specification: Daniel G. Bobrow, Linda G. DeMichiel, Richard P. Gabriel, Sonya E. Keene, Gregor Kiczales, and David A. Moon.
Richard was also the CEO and founder of Lucid, Inc. - a Common Lisp vendor. His company developed and sold a production quality Common Lisp implementation for various UNIX systems.
The review itself is really interesting, you get to learn the context around the MOP and where this book actually came from.