"Then I won't go! Imagine not smoking for two whole months! Do you think I have sworn off?"
"No, not yet. But you must. It pollutes the air, which we must keep clean and fresh as long as possible."
"Now, Doctor, you must let me have a good smoke once a day, just before pumping the air out of my compartment."
"No, not even that. It is impossible to pump all the air out, and what is left mixes back with what is in my compartment. Once contaminated with tobacco smoke, we could never get it perfectly pure again."
"Well, may I smoke on Mars, then? I will take them along for that. But, I warn you, I eat like a farm horse when I can't smoke."
"I have provided plenty to eat, but I know I have forgotten something. Mention something now, mention everything you can think of, so that I may see if it is provided for."
"Have you any money?" I asked. "I have changed some into gold, and have a fairly heavy bag here."
"Oh, yes, I have some gold and silver money, besides a lot of beads, trinkets, and gaudy tinsel things, such as earthly savages have been willing to barter valuable merchandise for."
"So you are going on a trading expedition, are you?" I asked.
"Not exactly. I leave all that to your superior abilities. But we may find these things valuable to give as presents. Many of them are of tin, and if they do not happen to have that useful metal on Mars, they will be of rare value there."