To Professor Mair of Liverpool is due the initial suggestion, and it has been felt a fitting tribute to his supervision, criticism, encouragement and sympathy that this book should be respectfully dedicated to him by one of his grateful pupils. In the labour of dealing with the proofs, the writer has to acknowledge the co-operation of Miss M. Linn and Mr. J. E. Turner, M.A. * * * * * * * * * The method adopted in this history has been deliberately chosen for its usefulness in emphasising the development of ideas. A purely chronological method has not been followed. The biographical system has likewise been rejected. The history of the development of thought centres round problems, and it progresses in relation to these problems. The particular manner in which the main problems presented themselves to the French thinkers of the second half of the nineteenth century was largely determined by the events and ideas which marked the period from 1789 to 1851. For this reason a chapter has been devoted to Antecedents. Between the Revolution and the _coup d’état_ of Napoleon III., four distinct lines of thought are discernible. Then the main currents from the year 1851 down to 1921 are described, with special reference to the development of the main problems. The reconciliation of _science_ and _conscience_ proved to be the main general problem, which became more definitely that of Freedom. This in itself is intimately bound up with the doctrines of progress, of history, of ethics and religion. These topics are discussed in a manner which shows their bearing upon each other. The conclusion aims at displaying the characteristics of French thought which reveal themselves in the study of these great problems. Its vitality, concreteness, clearness, brilliance and precision are noted and a comparison made between French thought and German philosophy.