This volume is written with the double purpose of telling the life-story of a man who devoted himself to the service of humanity, and of giving a succinct history of one of the most notable movements of modern times. The cause and the man are inseparable. Though a due meed of honour must be paid to others who have co-operated in the work that has been done, and especially to those early pioneers who, like Immanuel Kant, cherished "the sweet dream of perpetual peace," and sought to realise it, the foremost leader for a whole generation was the man whose history is herein recorded.