The last two chapters are devoted to Lie's development of Lie Algebras and his construction of the geometry from a continuous group and Klein's Erlanger Programm unifying the different approaches to geometry by emphasizing automorphism groups. These last pages are definitely the climax of the book. All of this only occupies the first half of the book, the second half consists of extensive notes to the former, intended to help the reader deepen her understanding of the subject in a second reading. I think this book is very readable and should be accessible to any interested reader who has a slight understanding of the terms used so far in this review