“Well then,” Calamy went on, “I have to imagine an almost inconceivable number of atoms, each consisting of a greater or lesser number of units of negative electricity whirling several million times a minute round a nucleus of positive electricity. The vibrations of the atoms lying near the surface sift out, so to speak, the electro-magnetic radiations which fall upon them, permitting only those waves to reach our eyes which give us the sensation of a brownish-pink colour. In passing it may be remarked that the behaviour of light is satisfactorily explained according to one theory of electro-dynamics, while the behaviour of the electrons in the atom can only be explained on a theory that is entirely inconsistent with it. Inside the atom, they tell us now, electrons move from one orbit to another without taking any time to accomplish their journey and without covering any space. Indeed, within the atom there is neither space nor time. And so on and so on. I have to take most of this on trust, I’m afraid, for I understand next to nothing about these things. Only enough to make me feel rather dizzy when I begin to think about them.” “Yes, dizzy,” said Mary, “that’s the word. Dizzy.” She made a prolonged buzzing over the z’s. “Well then, here are two ways already in which my hand exists,” Calamy went on. “Then there’s the chemical way. These atoms consisting of more or fewer electrons whizzing round a nucleus of greater or lesser charge are atoms of different elements that build themselves up in certain architectural patterns into complicated molecules.” Sympathetic and intelligent, Mary echoed: “Molecules.”