“Are there any experiments in intellectual philosophy?” asked Rollo.
“Yes,” said Mary, “we can try experiments in intellectual philosophy.”
“What experiments?” said Rollo.
“Why, there is a question whether we always dream when we are asleep.”
“I do,” said Rollo, “every night.”
“Yes, but perhaps not all night long.”
“Yes, I do,” said Rollo. “I have good long dreams.”
“But,” replied Mary, “you may dream several hours in the night, so as to remember good long dreams in the morning, and yet perhaps you might have been, for some time, perfectly sound asleep, so as not to have any dreams in your mind at all. Some persons think we dream all the time when we are asleep, and others think we don’t dream all the time. Now we might contrive some experiments to decide the question.”
“How?” said Rollo.
“Why, you and I might agree to wake each other up several times, from a sound sleep, and then, if we were dreaming at that time, we should probably remember it.”