This book, originally published in 1923, embodies two related and yet distinct types of sociological endeavour. It is a study in the history of social thought, a field which had only been receiving serious and widespread attention in recent years, and attempts to give an historical cross-section of representative Utopian thought at the time. But it is also a study in social idealism, a study in the origin, selection and potency of those social ideas and ideals that occasional and usually exceptional men conceive, with particular emphasis upon their relation to social progress. It was the first book that attempted to give an unprejudiced, systematic treatment of the social Utopias as a whole.