Students of psychology who have followed the modern trend of thought along the lines of mental phenomena are struck by the persistence of the dual-mind idea which has manifested itself so strongly during the past ten or fifteen years, and which has given rise to a number of plausible theories regarding the nature and constitution of these "two minds." The late Thomson J. Hudson attained great popularity in 1893 by advancing his well-known theory of the "objective and subjective minds" which he held existed in every individual. Other writers have attracted almost equal attention by the theories regarding the "conscious and subconscious minds"; the "voluntary and involuntary minds"; "the active and passive minds," etc., etc. The theories of the various writers differ from each other, but there remains the underlying principle of "the duality of mind." The student of the Hermetic Philosophy is tempted to smile when he reads and hears of these many "new theories" regarding the duality of mind, each school adhering tenaciously to its own pet theories, and each claiming to have "discovered the truth." The student turns back the pages of occult history, and away back in the dim beginnings of occult teachings he finds references to the ancient Hermetic doctrine of the Principle of Gender on the Mental Plane-the manifestation of Mental Gender. And examining further he finds that the ancient philosophy took cognizance of the phenomenon of the "dual mind," and accounted for it by the theory of Mental Gender. This idea of Mental Gender may be explained in a few words to students who are familiar with the modern theories just alluded to. The Masculine Principle of Mind corresponds to the so-called Objective Mind; Conscious Mind; Voluntary Mind; Active Mind, etc. And the Feminine Principle of Mind corresponds to the so-called Subjective Mind; Sub-conscious Mind; Involuntary Mind; Passive Mind, etc. Of course the Hermetic Teachings do not agree with the many modern theories regarding the nature of the two phases of mind, nor does it admit many of the facts claimed for the two respective aspects--some of the said theories and claims being very far-fetched and incapable of standing the test of experiment and demonstration. We point to the phases of agreement merely for the purpose of helping the student to assimilate his previously acquired knowledge with the teachings of the Hermetic Philosophy. Students of Hudson will notice the statement at the beginning of his second chapter of "The Law of Psychic Phenomena," that: "The mystic jargon of the Hermetic philosophers discloses the same general idea" i.e., the duality of mind. If Dr. Hudson had taken the time and trouble to decipher a little of "the mystic jargon of the Hermetic Philosophy," he might have received much light upon the subject of "the dual mind"--but then, perhaps, his most interesting work might not have been written. Let us now consider the Hermetic Teachings regarding Mental Gender.