Sir Henry Head (1861-1940) was an English physician and neurologist who worked extensively on sensory systems. Originally published in 1926, this book forms part of a two-volume work by Head on the subject of aphasia. The work was written in an attempt to analyse and integrate the physical and psychological aspects of the condition, incorporating them both into a general theory regarding linguistic expression. Illustrative figures are included. This book will be of value to anyone with an interest in aphasia and the history of medicine.