In Problems of Philosophy Russell attempts to create a brief and accessible guide to the problems of philosophy. He introduces important theories of Plato, Aristotle, René Descartes, David Hume, John Locke, Immanuel Kant, Georg Hegel and others to lay the foundation for philosophical inquiry. The Theory of Knowledge occupies a larger space than metaphysics in the present volume, and some topics much discussed by philosophers are treated very briefly, if at all.