Book excerpt: This book is a quantum mechanics text, written on the assumption that the purpose of learning quantum mechanics is to be able to understand the results of fundamental research into the constitution of the physical world. The text essentially concerns itself with three themes, these being a logical exposition of quantum mechanics, a full discussion of the difficulties in the interpretation of quantum mechanics, and an outline of the current state of understanding of theoretical particle physics, The reader is assumed to have some mathematical skill, but no prior knowledge of physics is assumed. The book will be used for final-year undergraduate courses in mathematics and physics, and of interest to professionals in philosophy and pure mathematics.