Although scholarly research has been lavished on several individual aspects of Augustine's views on the nature and activities of the mind and soul, it will be granted that no substantial monograph has been devoted to a general study of the topic since the pioneering work of Ferraz in the mid-nineteenth century. The main emphasis in the present work is on the analysis and elucidation of Augustine's arguments, particularly his more intricate and obscure ones. Occasional criticism of some of those arguments is thus inevitable, even when due allowance is made for their historical context: but it is my hope that an overall impression emerges of a gifted intelligence applying.