The present short treatise on the spirit of the fundamental principles of Ismailism forms a useful introduction to the study of the Ismaili doctrine in general, and especially as it developed in the Nizari school of the sect. It was intended by its author to reach everybody, the learned as well as the people of no great education, and therefore all technicalities or abstract and difficult theories have been carefully avoided. The author shows on many occasions a deep insight into the nature of the religious life of the human soul, and here and there lays open the most hidden psychological springs of the movement, in fact more than many works extant do.