Source Book Of Philosophy
Philosophy is a very wide subject to be covered in a single book. It has many branches, for example, epistemology, metaphysics, logic, and ethics, and there is an enormous amount of material available within each branch. Philosophy can also be studied by periods, for example, the pre-Socratic period, the Greek period, the modern period, etc. Moreover, philosophy can be studied by field of interest, for example, Philosophy of Science, Philosophy of Mathematics, and so on and so forth. If you are just starting out, you can pickup any entry level book on Greek philosophy, and then dig deeper and wider according to your areas of interest.