Though Professor Metchnikoff originally introduced "yougurth" as an antidote against the putrefactive bacteria of the human colon, he soon realized that the microbe-killer, inoculated in the system by the "yougurth," after having succeeded in cleaning out the native microbe of the intestine, proved to be a more difficult and dangerous tenant to handle than the one gotten rid of. In other words, the "yougurth" microbe holds the same relation to the cells and tissues of the human organism as the English sparrow to the Australian grain fields, where it had been sent to clean out the bugs and worms that menaced the seed. When the worms were gone, however, the sparrow, to sustain its own existence, proceeded to attack the grain itself, and thus became a far greater menace to the farmer than the old worm.
This practice of inoculating the human system with organized, laboratory-hatched microbe-killers, whether in the form of beverages, inhalations or serums, is a very costly business to the economy of human physiology. Partly because of the fact that the torn and racked body has to provide the battle field for the contending forces, and, partly because of having to sustain the invading army of conquest after the native enemy is routed - the drain of the alien occupation is experienced by the system in loss of strength, progressive breakdown and premature old age.
And this in the teeth of the fact that nature has provided the human organism with a "physiological defense," an "opsonic" reserve force, represented in the constitutional virility of every single cell of the body, in every speck of lymph in the tissues and in the mystic secretions of every "ductless" gland. In other words, the body is a commonwealth, equipped with a militia of organized protection, perfectly adequate to maintain its own defense, providing its government is maintained on a basis of natural and moral laws, and in conformity to the eternal principles of love and labor, which God has placed in the construction of the world for the guidance of humanity.
Be careful, not only of what goes out of your mouth, but of what goes into it. It is not the introduction into our system of alien uncontrollable agencies of complex serums that the individual requires for his continued growth in health and survival value, but the command of himself and a faith in the powers that work through him.