Symmetry in Mechanics: A Gentle, Modern Introduction"And what is the use," thought Alice, "of a book without pictures or conversations in it?" Lewis Carroll This book is written for modem undergraduate students not the ideal stu dents that mathematics professors wish for (and who occasionally grace our campuses), but the students like many the author has taught: talented but ap preciating review and reinforcement of past course work; willing to work hard, but demanding context and motivation for the