Five volumes have been written under the overall title of A Treatise on the Seven Rays, based on the fact, the nature, the quality and the interrelationship of the seven streams of energy pervading our solar system, our planet and all that lives and moves within its orbit. The two volumes of Esoteric Psychology go extensively into the psychological make-up of a human being as the life, quality and appearance of an incarnating, evolving spiritual entity. They also relate the circumstance of a human psychology to world conditions and to future possibilities. Psychology is defined in Webster's Dictionary as "the science of mind", at one time considered a branch of metaphysics. Today we are more inclined to include all the conditioning subjective factors as psychological in nature-mental and emotional impulses and soul contact, to whatever degree it exists. These subjective influences constitute the whole psychological background to a man's attitudes and behaviour, and create the faculty of spiritual response. The "psyche" is, after all, the human soul, the centre of consciousness. Esoteric psychology begins with a consideration of the human being as a soul, manifesting in the form of a personality, consisting of mental, emotional and etheric/physical substance, and more or less in contact and control, depending on the stage of evolution in the personality consciousness. From the point of view of esoteric psychology, evolution is the evolution of consciousness, by which the imbedded fragment of the soul within the personality progressively identifies its spiritual source and becomes at-one with it. The seven differentiated streams of ray energy play a significant role in this evolutionary process. A blend of five energies in a human being determine his goals, his problems, his available qualities and energy resources, and the correct method by which--according to his dominant ray influence--he may unfold his consciousness and make spiritual progress.