The number of the “American Journal of Insanity” Vol. xxxiv. No. 3, contains the address on “Mental Hygiene,” delivered by Dr. Gray, the Editor, at the International Medical Congress, at Philadelphia. To cite all the passages which convey the principal truths which Dr. Gray wishes to enunciate in his terse and striking language would occupy a large part of the space at our disposal. The term is certainly employed in a very comprehensive sense. It “covers all the broad field of human energy, embracing all the professions and every branch of industrial life. It looks after man's moral as well as his intellectual nature, for the two cannot be separated. It enters into his domestic and social conditions, and follows him in his duties as a citizen.” The problem is no less than to discover the best scheme for the development of human nature and the control of his passions.