When he first entered the opening, Aaron surely knew which way was up. He also had a certainty that he could find his way back, especially after he located the stairwell leading downward.
Somehow though, between the heaviness of the air and the extreme darkness, Aaron realized he was confused. He stopped, trying to gather his senses, and to make a decision: continue down or head upward.
Finally, decision made, Aaron turned back the way he had come, and yet he felt he was still going deeper into the hole. “This is what becomes of chasing white rabbits,” he complained.