“ ‘Right,’ assented Zinotchka. ‘Plants, on the contrary, breathe in carbonic acid gas, and breathe out oxygen. Carbonic acid gas is contained in seltzer water, and in the fumes from the samovar.⁠ ⁠… It is a very noxious gas. Near Naples there is the so-called Cave of Dogs, which contains carbonic acid gas; a dog dropped into it is suffocated and dies.’

“This luckless Cave of Dogs near Naples is a chemical marvel beyond which no governess ventures to go. Zinotchka always hotly maintained the usefulness of natural science, but I doubt if she knew any chemistry beyond this Cave.

“Well, she told me to repeat it. I repeated it. She asked me what was meant by the horizon. I answered. And meantime, while we were ruminating over the horizon and the Cave, in the yard below, my father was just getting ready to go shooting. The dogs yapped, the trace horses shifted from one leg to another impatiently and coquetted with the coachman, the footman packed the wagonette with parcels and all sorts of things. Beside the wagonette stood a brake in which my mother and sisters were sitting to drive to a name-day party at the Ivanetskys’. No one was left in the house but Zinotchka, me, and my eldest brother, a student, who had toothache. You can imagine my envy and my boredom.

“ ‘Well, what do we breathe in?’ asked Zinotchka, looking at the window.

“ ‘Oxygen⁠ ⁠…’

“ ‘Yes. And the horizon is the name given to the place where it seems to us as though the earth meets the sky.’