The Principles of Quantum Mechanics by P.A.M. Dirac is one of the most influential and foundational works in theoretical physics. In this book, Dirac presents a rigorous and systematic formulation of quantum mechanics, introducing the abstract mathematical framework that underpins the theory. The work covers the use of operators, state vectors, transformation theory, and the general principles governing quantum measurements, offering a unified and highly original approach to the subject. Renowned for its clarity and depth, the book has played a decisive role in shaping modern quantum theory and has served as a core reference for physicists and mathematicians for decades. This third edition belongs to the early authoritative printings of this landmark work and dates from the formative period during which quantum mechanics became firmly established as a central discipline in physics. Early editions of Dirac’s principal work are sought after by collectors of scientific literature due to their historical importance, lasting scientific relevance, and association with one of the key figures in twentieth-century physics. This item will be carefully packed and shipped with a track-and-trace code.