'Like Copernicus and Darwin—the comparison has become inevitable—' Freud 'put the facts of common observation in a setting which profoundly altered their meaning, and which introduced into both science and common knowledge radically new perspectives. But unlike Copernicus and Darwin, Freud presented his theories in a form unsuitable to scientific verification and use. The situation abounds in difficulties and recalls the half despairing advice given by William James in another connection: "The only thing then is to use as much sagacity as you possess and to be as candid as you can".'

This concluding sentence is elaborated in a fair, clear, and stimulating way. Many well-known facts, presented in a new light, as well as a number of new details, make the article worth reading.