This is a new publication of Eddington's book The Philosophy of Physical Science. It contains the following chapters: Scientific Epistemology; Selective Subjectivism; Unobservables; The Scope of Epistemological Method; Epistemology and Relativity Theory; Epistemology and Quantum Theory; Discovery or Manufacture? The Concept of Analysis; The Concept of Structure; The Concept of Existence; The Physical Universe; The Beginnings of Knowledge; The Synthesis of Knowledge.