The Spiritual Theory is the first scientific theory that seeks to explain spiritual phenomena and their relationship to the material world, in addition to providing a coherent explanation of the spiritual origin of matter in the universe. Spiritual Theory explains evolution through the intelligent action of the incarnated Spiritual Elements and proposes accurate models to explain the origin and composition of the perispirit, the peribody, the fluidic link, the mind, and mediumship, among others. This theory explains how from the increased harmony of the spirit's attributes emerge the moral laws that define the intimate relationships of all that exists. This theory could be considered the theory of everything.