Comparatively few health enthusiasts or food reformers realise the necessity for mental, as distinct from bodily, hygiene, yet all real health has its roots in the mind. Moreover, it is only by studying the hygiene of mind that we are enabled to do work in greater quantity and of better quality than we should otherwise be capable of, and to do this without risk of strain on the nerves or injury to health. The articles under this heading put forward some of the elementary laws of mental hygiene. - [Eds.]