Lecture X

And now to begin with let us leave aside everything that man has from the Earth-epoch—thereby making our further studies of this all the more fruitful—and let us take the metabolic system as such, which, though certainly developed as an Earth-organization, nevertheless received its germinal beginnings from the epoch of old Moon. Let us therefore take digestion in the narrower sense of what takes place inside the human skin—in which we must of course include the excretory processes—and we shall find that all substances become altered in the intake of food. The food-substances, which at first are outside man, enter into him, and merge themselves with the digestive system. This digestive system now converts what belonged to man's surroundings into what is essentially human. Everything mineral begins to assume the condition of warmth-ether, everything vegetable the gaseous-airy-vaporous condition, everything animal, including what is self-produced, begins to assume the fluid condition; and all begin to build what is now essentially human into a firmly organized structural form. All this is inherent in digestion. And digestion is consequently something of remarkable interest.