Bertrand Russell 
The Analysis of Mind 

This book established a new conception of the mind and provided one of the most original and interesting externalist accounts of knowledge. Drawing upon the writings of psychologists such as William James and John Watson, Russell offers a comprehensive treatment of such considerations as belief, desire, habit, memory, meaning, and causal law. His reasoning formed the foundation for many subsequent theories of mind, as well as a framework for his own later philosophical writings. It remains one of the most important works on the philosophy of the mind.