Another writer in a recent publication makes use of an analogous illustration by describing human personality as an iceberg, the great bulk of which is always invisible and submerged.[45] The matter is further complicated by the fact that within the domain of the subconscious there exists a vitality which cannot be traced to a cerebral or somatic source. Stated in broad terms it may be said that mind, or the sum total of Personality, must be viewed in two interactionary aspects: the primary consciousness and secondary consciousness, or the conscious and the subconscious or subliminal or (in a special sense) subjective, according to the various terms used by different writers to express the same thing. For the purpose of greater lucidity, it has usually been found that this dual aspect of mind can be best expressed by treating the whole mental organization as consisting of two minds, each endowed with separate and distinct attributes and powers; each capable, under certain conditions, of independent action. It may be that a truer idea would be conveyed if the mind-whole was described as possessing certain attributes and powers under some conditions, and certain other attributes and powers under other conditions. As my object, here, is to enter no further into psychological questions than is necessary for the elucidation of those ethical considerations which are dependent upon them, I shall give a short account of those theories which, in the light of present knowledge, appear best founded and afford most assistance in connexion with the subject of morality. Thomas J. Hudson, whose hypothesis I shall make use of to illustrate my meaning, assumed for practical purposes that man has two minds. In making use to some extent of Hudson's theory, I do so not because it is necessarily correct, for his hypothesis was, admittedly, to a certain extent provisional; but because it was the first practical working hypothesis on which all psychic and hypnotic phenomena could be based, and because it has largely been used as a basis for subsequent elaborations. In 1892, Hudson, in his "Law of Psychic Phenomena," said: "In more recent years the doctrine of duality of mind is beginning to be more clearly defined, and it may now be said to constitute a cardinal principle in the philosophy of many of the ablest exponents of the new psychology." To-day when psychotherapeutics have claimed the attention of students of pathology, and when at last the medical profession has almost throughout enlisted the co-operation and help of hypnotism, there are far fewer people who would deny the existence of that substratum of consciousness, distinct from the manifestation of the normal waking mind, which is so profitably studied in the phenomena of somnambulism, hypnotism and lunacy.