"This book is one recent product of her work on this subject, which first saw light as a dissertation, then in a series of papers, and now appears in a revised and expanded version of her early work for the History of Analytic Philosophy series ... . The perspective van der Schaar brings here is ... a valuable addition to the detailed account of the early development of analytic philosophy at Cambridge." (Consuelo Preti, Journal of the History of Analytical Philosophy, Vol. 4 (3), 2016)