This is the first English translation of Condillac's most influential works: the Essay on the Origins of Human Knowledge (1746) and Course for Study of Instruction of the Prince of Parma (1772). The Essays lay the foundation for Condillac's theory of mind. He argues that all mental operations are, in fact, sensory processes and nothing more. An outgrowth of Locke's empirical account of ideas and sensations as a source of knowledge, Condillac's theory goes beyond Locke's foundations, introducing his universal method for understanding any complex entity: the reduction of all matters to their origins and then to their simplest forms. The Course, originally written to teach Prince Ferdinand of Parma to think and to develop good habits of mind following the principle of association of ideas, covers grammar, writing, reasoning, thinking, and ancient and modern history. Philip writes in the introduction: "[the] mind is moldable to reason and to 'nature' which gave it a model and provides the ultimate authority for all it can know or do."

This highly readable translation of the major works of the 18th- century philosopher Etienne Bonnot, Abbe de Condillac, a disciple of Locke and a contemporary of Rousseau, Voltaire, and Diderot, shows his influence on psychiatric diagnosis as well as on the education of the deaf, the retarded, and the preschool child. Published two hundred years after Condillac's death, this translation contains treatises which were, until now, virtually unavailable in English: A Treatise on Systems, A Treatise of the Sensations, Logic.

A treatise on systems -- A treatise on the sensations -- Logic, or the first developments of the art of thinking.

This text covers such topics as value, money, agriculture, domestic and foreign trade, war, labour, interest rates, luxuries, and the various government policies that affect these subjects. The theme that unites these disparate subjects is liberty. As Condillac writes near the end of the work, the means to eradicate all the abuses and injustices of government is "to give trade full, complete and permanent freedom". In their preface to the 1997 edition, Shelagh and Walter Eltis wrote, "English language readers . . . will find . . . that the case for competitive market economics has rarely been presented more powerfully."