Originally published in 1940 Firstly this book seeks to combine epistemology and the new developments of the time in psychology It holds that no epistemology can be sound if it is psychologically defective nor can a psychological analysis of knowledge be philosophically naive Secondly it attempts to suggest a single structural pattern underlying every type of cognitive situation Offering a significant reorientation to epistemological thought of its time this work considers perception sense and memory and examines the referential theory of knowledge It is a lucid and precisely organised reading and analysis of knowledge