Our intellectual grasp extends throughout the cosmos, and has brought to light the material processes going on at every scale-from the thermonuclear furnaces of the stars, down through the protein-factories of the cytoplasm, to the changes of wave-pattern which take place when an atom swallows a photon. And this intellectual grasp is paralleled and completed when we turn to the practical sphere. We have exceeded the dreams of the craftsmen, the alchemists and the medicine-men, and by now we have the means either to satiate or to destroy ourselves.