The only element common to the thirteen pieces of this collection is the time of their composition: the span of World War I, during which Teilhard served as a stretcher-bearer with the French army. The essays do not reflect the conflagration in the midst of which they were written, but outline the wide range of philosophical and theological interests which were to come to full flower in later works. Among them, ""Cosmic Life"" is the record of an awakening to the world and of an initial temptation to pantheism, the latter counterbalanced by the necessity for a transcendental unity. ""Mastery of the World"" discusses the adaptation of the apostolate to the needs of the world. ""The Priest"" presages The Mass on the World of 1923, as does ""The Mystical Milicu"" the Milicu Divin of 1927. ""Creative Union"" and ""The Struggle Against the Multitude"" explore the relationship between the one and the many in the universe, the former from the pragmatic and empirical standpoint and the latter from the metaphysical. The various essays are ordered chronologically rather than topically, which is often inconvenient e.g., ""Struggle Against the Multitude"" and ""Creative Union"" are separated by ""Mystical Milieu,"" although they should be read together since ""Union"" was intended by Teilhard to correct and complement ""Struggle."" Moreover, Teilhard himself mentioned in a letter of a later period that his war-time writings ""contain nothing that I have not said more clearly at a later date."" This collection, therefore, is for the scholar who is concerned with the evolution of Teilhard's though rather than for the reader who is interested in his teachings.