Condillac's Essay on the Origin of Human Knowledge, first published in French in 1746 and offered here in a new translation, represented in its time a radical departure from the dominant conception of the mind as a reservoir of innately given ideas. Descartes had held that knowledge must rest on ideas; Condillac turned this upside down by arguing that speech and words are the origin of mental life and knowledge. His work influenced many later philosophers, and also anticipated Wittgenstein's view of language and its relation to mind and thought.