On page 528 of _Preventive Medicine and Hygiene_, by Rosenau, we read: “We are still ignorant of the mechanism by which the body protects itself against many dis-eased states.” He also gives us the idea that the mechanism of immunity varies not only in different infections, but in the same infection when under different and varying conditions. Natural Immunity Immunity is classed as natural, acquired and artificial. Natural immunity is that natural resistance of Innate Intelligence through the activity in the normal body whereby all invading organisms and poisons, as well as all the products of katabolism are excreted before they have an opportunity to act upon the tissues or otherwise interfere with the vital processes in the body. Acquired Immunity Acquired immunity is the result of the adaptative processes of Innate Intelligence during the time the so-called dis-ease is active in the body which results in the recovery of the patient. To illustrate: During the attack of measles there is an adaptative process carried on which results in the recovery of the patient. During the process of this adaptation Innate produces changes in the body which makes possible the excretion of this kind of poison when introduced into the body in the future. It is a recognized fact, however, that having a dis-ease will not always prevent the recurrence of the dis-ease. In other words, to put it in the terminology familiar to all, having a dis-ease will not always produce immunity. Artificial Immunity Artificial immunity is classified as active and passive. George M. Price, M.D., in his _Hygiene and Public Health_, says: “Active immunity is produced by the following conditions: (1) Recovery from dis-ease. (2) Inoculation with virulent living bacteria. (3) Vaccination with attenuated bacteria; (4) with dead bacteria; (5) with bacterial extracts. Passive immunity is conferred by antitoxins and serums.” The idea here presented is that the immunity is active if it is the result of a necessity for internal intellectual adaptation on the part of Innate Intelligence, and when this adaptation takes place there will be immunity from further attacks. That the passive immunity is produced by the introduction of antitoxins or serums taken from the bodies of animals in whose bodies these adaptative processes have taken place. There is no possible way of producing immunity except by creating a condition in the body which will enable Innate Intelligence to transmit the mental impulses to the tissues in such quantity and quality that there may be perfect adaptation carried on regardless of the character of the poison or microörganism that may be introduced into or manufactured within the body. Exhaustion Theory