In his brilliant and tragically brief career, Kenneth Craik anticipated certain ideas which since his death in 1945 have found wide acceptance. As one of the first to realise that machines share with the brain certain principles of functioning, Craik was a pioneer in the development of physiological psychology and cybernetics. Craik published only one complete work of any length, this essay on The Nature of Explanation. Here he considers thought as a term for the conscious working of a highly complex machine, viewing the brain as a calculating machine which can model or parallel external events, a process that is the basic feature of thought and explanation. He applies this view to a number of psychological and philosophical problems (such as paradox and illusion) and suggests possible experiments to test his theory. This book is of interest to those concerned with the concepts of brain and mind.