“Hitherto it had touched him on the intellectual side alone; but now his imagination also was engaged, or rather enslaved; and as he lay and tossed in the gross darkness of the night and the curtained room, Mr. Enfield’s tale went by before his mind in a scroll of lighted pictures.”

In Dr. Jekyll and Mr. Hyde, characters struggle to control the irrational side of their minds. In this quote about Mr. Utterson, Utterson is gripped by Mr. Enfield’s tale about Mr. Hyde as he is home alone in bed, tossing and turning. In the daytime, his rational mind prevails, and his intellectual mind is able to keep the story in check, but at night, his imagination is engaged, and the story engrosses him. Utterson’s curiosity is drawing him into Enfield’s tale.

“If he could but once set eyes on him, he thought the mystery would lighten and perhaps roll altogether away, as was the habit of mysterious things when well examined.”

In Chapter 2, Utterson is trying to convince himself that once he sees Hyde, he will be able to free himself from his curiosity about him, which is growing by the hour. Utterson’s confidence that rational examination of the facts would clear up the mystery highlights his position as a respectable lawyer in the Victorian era. The story throws this common Victorian assumption into question, as rational examination fails to satisfy many of the characters in the face of mysterious, supernatural events.

“Five minutes afterwards, if you insist upon an explanation, you will have understood that these arrangements are of capital importance; and that by the neglect of one of them, fantastic as they must appear, you might have charged your conscience with my death or the shipwreck of my reason.”

In Jekyll’s letter to Dr. Lanyon, one can see how just how deteriorated Jekyll’s state of mind has become, even if the reason why is not yet clear. Jekyll’s mind is so compromised that if Lanyon fails to carry out his requests, Jekyll worries his sanity might be irreversibly compromised. Like many of the characters in Dr. Jekyll and Mr. Hyde, Jekyll’s rational mind is under threat by the unexplainable, mysterious supernatural events Jekyll has put into motion.

“‘We had,’ was the reply. ‘But it is more than ten years since Henry Jekyll became too fanciful for me. He began to go wrong, wrong in mind; and though of course I continue to take an interest in him for old sake’s sake, as they say, I see and I have seen devilish little of the man. Such unscientific balderdash,’ added the doctor, flushing suddenly purple, ‘would have estranged Damon and Pythias.’”

In Chapter 2, we get an early glimpse into the nature of Dr. Lanyon and Jekyll’s friendship. Both are doctors and men of science, but Dr. Lanyon believes that Henry Jekyll became isolated by radical views, straying too far from the orthodoxy of their scientific profession. Lanyon equates Jekyll’s unconventional pursuits with a preoccupation with irrational matters. Lanyon’s reference to the legendary friendship of Damon and Pythias indicates he once felt close to Jekyll, and he chokes up with emotion just talking about the subject. This strain in their professional relationship gives pathos to Jekyll’s turning to Lanyon for help later.

“It is well,” replied my visitor. “Lanyon, you remember your vows: what follows is under the seal of our profession. And now, you who have so long been bound to the most narrow and material views, you who have denied the virtue of transcendental medicine, you who have derided your superiors—behold!”

In Dr. Lanyon’s last letter, he recounts Jekyll’s words to him before Jekyll reveals himself as Hyde. Jekyll chided Lanyon for being close-minded in his dismissal of scientific inquiries that go beyond the realm of materialism. Jekyll thus gloats as the revelation of Hyde sends Lanyon into shock. Lanyon is unable to understand or accept what he has seen. Lanyon’s rational mind, when confronted with the irrational, simply collapses.