The years 1909-1913 were among the most productive, philosophically speaking, of Bertrand Russell's entire career. In addition to the papers reprinted in this volume, he brought Principia Mathematica to its finished form and wrote The Problems of Philosophy, Theory of Knowledge and Our Knowledge of the External World.

In October 1910, Russell began teaching at Cambridge, having accepted an appointment as lecturer in logic and the principles of mathematics at Trinity College for a term of five years. The following year, Ludwig Wittgenstein began to attend his lectures. Within a few months, Wittgenstein had exerted a major influence on Russsell's philosophical thinking, perhaps even more than Russell had influenced his thought.