Here, Lewis struggles with the disconnect between his knowledge of Ransom as trustworthy and his more instinctual feeling that this might not actually be the case. That he continues to press on, though, suggests that when faced with fear, people must sometimes go against what they feel and instead rely on their reason. That’s particularly difficult when, as here, fear makes someone feel that their reason is under direct attack. This passage also introduces Maleldil, who appears to be a god figure.